fix(ci): clone upstream locally instead of using repo-url for changelog

The rpm-changelog action's repo-url input uses mktemp which fails on
runners with restricted /tmp permissions. Clone the upstream repo
directly in the workflow and use source-dir instead.

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

.gitea/workflows/build-release.yml

@@ -94,12 +94,17 @@ jobs:
         env:
           TAG: ${{ inputs.tag }}
 
+      - name: Clone upstream for changelog
+        run: |
+          git clone --depth 50 --branch "${{ inputs.tag }}" \
+            https://github.com/EricLBuehler/mistral.rs.git upstream/
+
       - name: Generate changelog
         uses: https://git.lair.cafe/actions/rpm-changelog@v1
         with:
           spec: rpm/mistralrs.spec
           version: ${{ steps.version.outputs.version }}
-          repo-url: https://github.com/EricLBuehler/mistral.rs.git
+          source-dir: upstream/
 
       - name: Build RPM
         run: |