ios: simplify CI signing keychain setup

.gitea/workflows/testflight.yml

@@ -8,7 +8,7 @@ on:
 
 jobs:
   testflight:
-    runs-on: xcode
+    runs-on: macos-arm64
     defaults:
       run:
         shell: bash
@@ -33,10 +33,17 @@ jobs:
             brew install xcodegen
           fi
 
+      - name: Runner diagnostics
+        run: |
+          set -euo pipefail
+          whoami
+          printf 'HOME=%s\n' "$HOME"
+          security default-keychain -d user || true
+          security list-keychains -d user || true
+
       - name: Upload to TestFlight
         working-directory: ios
         env:
-          HOME: /var/lib/act_runner
           APP_STORE_CONNECT_KEY_ID: ${{ secrets.APP_STORE_CONNECT_KEY_ID }}
           APP_STORE_CONNECT_ISSUER_ID: ${{ secrets.APP_STORE_CONNECT_ISSUER_ID }}
           APP_STORE_CONNECT_KEY_CONTENT: ${{ secrets.APP_STORE_CONNECT_KEY_CONTENT }}
@@ -47,6 +54,5 @@ jobs:
           FASTLANE_SKIP_UPDATE_CHECK: "1"
           FASTLANE_XCODEBUILD_SETTINGS_TIMEOUT: "120"
         run: |
-          export PATH="/Users/runner/hostedtoolcache/Ruby/3.1.7/arm64/bin:${PATH}"
           ruby --version
           bundle exec fastlane ios beta