ci: harden GitHub Actions workflows and add zizmor scan

Adds a CI job that runs the zizmor static analyzer over the workflow
files under .github/, and applies the corresponding hardening so the
existing workflows pass the audit:

- add persist-credentials: false to every actions/checkout step that
  lacked it
- narrow top-level permissions: read-all to permissions: contents: read
- add a 7-day cooldown to the dependabot update entries

This is a CI/configuration-only change; no library code, tests, or
documentation are affected.

Author: antonwolfy

.github/dependabot.yml

@@ -5,6 +5,8 @@ updates:
     schedule:
       interval: "weekly"
       day: "saturday"
+    cooldown:
+      default-days: 7
     rebase-strategy: "disabled"
     labels: ["autoupdate"]
     groups:
@@ -16,6 +18,8 @@ updates:
     schedule:
       interval: "weekly"
       day: "saturday"
+    cooldown:
+      default-days: 7
     rebase-strategy: "disabled"
     labels: ["autoupdate"]
     groups:

.github/workflows/build-with-clang.yml

@@ -6,7 +6,8 @@ on:
       - master
   pull_request:
 
-permissions: read-all
+permissions:
+  contents: read
 
 jobs:
   build-with-clang:
@@ -51,6 +52,7 @@ jobs:
       - name: Checkout repo
         uses: actions/checkout@3d3c42e5aac5ba805825da76410c181273ba90b1 # v7.0.1
         with:
+          persist-credentials: false
           fetch-depth: 0
 
       - name: Install mkl-service dependencies

.github/workflows/build-with-standard-clang.yml

@@ -5,7 +5,8 @@ on:
   push:
     branches: [master]
 
-permissions: read-all
+permissions:
+  contents: read
 
 jobs:
   build-with-standard-clang:
@@ -42,6 +43,7 @@ jobs:
       - name: Checkout repo
         uses: actions/checkout@3d3c42e5aac5ba805825da76410c181273ba90b1 # v7.0.1
         with:
+          persist-credentials: false
           fetch-depth: 0
 
       - name: Install mkl-service dependencies

.github/workflows/build_pip.yml

@@ -6,7 +6,8 @@ on:
       - master
   pull_request:
 
-permissions: read-all
+permissions:
+  contents: read
 
 jobs:
   build:
@@ -27,6 +28,7 @@ jobs:
     steps:
       - uses: actions/checkout@3d3c42e5aac5ba805825da76410c181273ba90b1 # v7.0.1
         with:
+          persist-credentials: false
           fetch-depth: 0
 
       - uses: conda-incubator/setup-miniconda@8ee1f361103df19b6f8c8655fd3967a8ecb162d5 # v4.0.1

.github/workflows/conda-build-test.yml

@@ -29,7 +29,8 @@ on:
         default: false
         type: boolean
 
-permissions: read-all
+permissions:
+  contents: read
 
 env:
   module-name: mkl
@@ -69,6 +70,7 @@ jobs:
       - name: Checkout repo
         uses: actions/checkout@3d3c42e5aac5ba805825da76410c181273ba90b1 # v7.0.1
         with:
+          persist-credentials: false
           fetch-depth: 0
 
       - name: Setup miniconda

.github/workflows/conda-package-cf.yml

@@ -6,7 +6,8 @@ on:
       - master
   pull_request:
 
-permissions: read-all
+permissions:
+  contents: read
 
 concurrency:
   group: ${{ github.workflow }}-${{ github.ref }}

.github/workflows/conda-package.yml

@@ -6,7 +6,8 @@ on:
       - master
   pull_request:
 
-permissions: read-all
+permissions:
+  contents: read
 
 concurrency:
   group: ${{ github.workflow }}-${{ github.ref }}

.github/workflows/openssf-scorecard.yml

@@ -16,7 +16,8 @@ on:
     branches: [ "master" ]
 
 # Declare default permissions as read only.
-permissions: read-all
+permissions:
+  contents: read
 
 jobs:
   analysis:

.github/workflows/pre-commit.yml

@@ -5,7 +5,8 @@ on:
   push:
     branches: [master]
 
-permissions: read-all
+permissions:
+  contents: read
 
 jobs:
   pre-commit:
@@ -15,6 +16,7 @@ jobs:
     - name: Checkout repo
       uses: actions/checkout@3d3c42e5aac5ba805825da76410c181273ba90b1 # v7.0.1
       with:
+        persist-credentials: false
         # use commit hash to make "no-commit-to-branch" check passing
         ref: ${{ github.sha }}
 

.github/workflows/zizmor.yml

@@ -0,0 +1,39 @@
+name: Security scan of GitHub Actions workflows (zizmor)
+
+on:
+  push:
+    branches:
+      - master
+  pull_request:
+
+permissions: {}
+
+concurrency:
+  group: ${{ github.workflow }}-${{ github.head_ref || github.run_id }}
+  cancel-in-progress: true
+
+jobs:
+  zizmor:
+    name: Scan GitHub Actions workflows
+
+    runs-on: ubuntu-latest
+    timeout-minutes: 10
+
+    permissions:
+      contents: read # needed to clone the repo
+
+    steps:
+      - name: Checkout mkl-service repo
+        uses: actions/checkout@3d3c42e5aac5ba805825da76410c181273ba90b1 # v7.0.1
+        with:
+          persist-credentials: false
+
+      - name: Run zizmor
+        uses: zizmorcore/zizmor-action@70fb788f84895a7701f5643d103d587e460b5c99 # v0.6.3
+        with:
+          # Low/informational template-injection notes come from internally-defined
+          # values (no external input), so they are reported as annotations but do not gate CI
+          min-severity: medium
+          advanced-security: false
+          annotations: true
+          inputs: .github/