fix: Update gratitude submodule to latest (v1.2.1) which fixes steam licenses page changes

[BlythT]

https://github.com/BlythT/Gratitude-Millennium-Plugin/releases/tag/v1.2.1

Gratitude - Gifted Games Reminder

Steam updated their licenses page (https://store.steampowered.com/account/licenses/) to be paginated (100 entries per page) where it listed all entries before.

Gratitude scrapes this page to get license information (as there is no official or undocumented licenses API I can find). As such, this is a breaking change for Gratitude (only the first 100 most recent licenses were being cached). I have updated the plugin to use the new paginated licenses page.

Alongside this, a bunch of other tidy-up and improvements that hadn't made it into a release are now in.

Task Checklist

Developer

• I am the original author or an authorized maintainer of this plugin.
• I have complied with all license requirements for the libraries used, including providing appropriate notices where necessary.
• My plugin is fully open source and does not depend on any external paid services, except for widely trusted and well-known platforms. Additionally, neither I nor anyone associated with me profits from any such services.

Plugin Functionality

• I have tested the plugin on both the Stable and Beta Steam update channels.

Backend Configuration

• No: I use a standard Millennium python backend in my plugin. (I use Lua)
• No: I use custom binaries that or rely on other FOSS projects that aren't written directly using Millennium's python backend.

Community Contribution

• I have tested and left feedback on two other plugin pull requests.
• I have added links to those feedback comments in this PR.

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Testing Instructions

Basic usage:

1. Install the plugin https://github.com/BlythT/Gratitude-Millennium-Plugin/releases/tag/v1.2.1
2. When asked for consent to store your license information, you should accept.
   a. You will be redirected to the store page (as described by the consent modal), which will automatically fetch your licenses the the background
3. Navigate to your library and select a game
   a. For non-gifted games you should see no change
   b. For gifted games you should see a "Gifted" tooltip near Playtime and Achievements with a present icon

Advanced use (optional):

4. Click the icon, see confetti. Click the label, see the gifter attribution form
5. Fill out the gifter attribution form (test the friend fetching and auto-fill if you like but these are non-critical)
6. Once submitted, when you mouse over the Gifted tooltip, it will say who gifted it to you, optionally including the note.

• Verified by a third party on Steam Client Stable.
• Verified by a third party on Steam Client Beta.

[BlythT]

Tested: #201 (comment)

[BlythT]

Tested No. 2: #205 (comment)