Bump dart_bridge to 1.9.0

dart_bridge 1.9.0 adds serious_python_hard_exit, which terminates the process
without running atexit handlers or C++ static destructors.

Embedders were seeing a SIGSEGV on exit: the interpreter runs on a detached
thread that may still be executing native extension code when the host quits,
and a normal exit() runs __cxa_finalize, destroying the C++ statics inside
every loaded extension module out from under it. The reported case died in
matplotlib's ft2font looking up a pybind11 type-caster map that had just been
destructed.

No Python versions change. This re-release exists to publish the updated
manifest so serious_python can regenerate its version tables against it.

See flet-dev/dart-bridge#20.

Author: FeodorFitsner

manifest.json

@@ -1,6 +1,6 @@
 {
   "default_python_version": "3.14",
-  "dart_bridge_version": "1.8.0",
+  "dart_bridge_version": "1.9.0",
   "pythons": {
     "3.12": {
       "full_version": "3.12.14",