fix(ci): grant contents:write to the Gitea release job

The top-level `permissions: contents: read` added alongside the zizmor
hardening applies to the release job too, and Gitea honours it: the built-in
gitea-actions token became read-only, so `tea releases create` failed with
"user should have a permission to write to a repo" (run 759).

The .github workflow already narrowed write to its release job; the Gitea
workflow has a single job and was left read-only. Grant it contents: write,
keeping the read-only default at the top level.

.gitea/workflows/release.yml

@@ -12,6 +12,8 @@ jobs:
   release:
     runs-on: cpu
     timeout-minutes: 20
+    permissions:
+      contents: write
     steps:
       - name: Checkout
         uses: actions/checkout@11d5960a326750d5838078e36cf38b85af677262 # v4.4.0