install pnpm differently

.gitea/workflows/tests.yaml

@@ -15,8 +15,13 @@ jobs:
       - name: Check out code
         uses: actions/checkout@v3
 
-      - name: Enable Corepack
-        run: corepack enable
+      - name: Setup pnpm
+        uses: pnpm/action-setup@v4
+        with:
+          version: 9
+          run_install: |
+            - recursive: true
+              args: [--frozen-lockfile, --strict-peer-dependencies]
 
       - name: Setup node
         uses: actions/setup-node@v4