ci: keep both platform exports running on failure

Gitea 28.0.0 now enforces strategy.fail-fast: true by default. Without
this, a failed Windows export cancels the Linux export job before it
finishes, instead of both platforms completing independently like
before the upgrade.

Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>

.gitea/workflows/release.yml

@@ -23,6 +23,7 @@ jobs:
     runs-on: ubuntu-24.04
     container: barichello/godot-ci:4.6
     strategy:
+      fail-fast: false
       matrix:
         include:
           - name: Windows