Pin CI free-threaded runs to CPython 3.14.0t

Update the standard-small and standard-large GitHub Actions jobs to
request python-version 3.14.0t instead of 3.14t. This forces setup-python
to use the last-known-good 3.14.0 free-threaded build rather than the
newer 3.14.1+ builds where subinterpreter finalization regressed.

Author: rwgk

.github/workflows/ci.yml

@@ -36,7 +36,7 @@ jobs:
       matrix:
         include:
           - runs-on: ubuntu-latest
-            python-version: '3.14t'
+            python-version: '3.14.0t'
             cmake-args: -DCMAKE_CXX_STANDARD=17 -DPYBIND11_TEST_SMART_HOLDER=ON
 
 
@@ -54,10 +54,10 @@ jobs:
       matrix:
         include:
           - runs-on: macos-latest
-            python-version: '3.14t'
+            python-version: '3.14.0t'
             cmake-args: -DCMAKE_CXX_STANDARD=20
           - runs-on: windows-latest
-            python-version: '3.14t'
+            python-version: '3.14.0t'
             cmake-args: -DCMAKE_CXX_STANDARD=23
 
     name: 🐍