ci: install bun from the npm registry (GitHub release assets answer 504 now and then), bun.sh with retries as fallback

.forgejo/workflows/release.yml

@@ -61,7 +61,7 @@ jobs:
       - name: Tag, package.json version, every version copy and the CHANGELOG agree
         id: check
         run: |
-          curl -fsSL https://bun.sh/install | bash -s "bun-v${BUN_VERSION}" >/dev/null
+          bash tools/ci-install-bun.sh
           echo "$HOME/.bun/bin" >> "${FORGEJO_PATH:-$GITHUB_PATH}"
           export PATH="$HOME/.bun/bin:$PATH"
           bun tools/desktop-version.ts