ci: pin actions to commit SHAs to prevent RCE

Pin actions/checkout and actions/setup-go to their full commit
SHAs instead of mutable tags, per review feedback.

- actions/checkout@v4 → 34e114876b0b11c390a56381ad16ebd13914f8d5
- actions/setup-go@v5 → 40f1582b2485089dde7abd97c1529aa768e1baff

.gitea/workflows/check.yml

@@ -0,0 +1,26 @@
+name: Check
+
+on:
+  push:
+    branches: [main]
+  pull_request:
+    branches: [main]
+
+jobs:
+  check:
+    runs-on: ubuntu-latest
+    steps:
+      - uses: actions/checkout@34e114876b0b11c390a56381ad16ebd13914f8d5 # v4
+
+      - uses: actions/setup-go@40f1582b2485089dde7abd97c1529aa768e1baff # v5
+        with:
+          go-version-file: go.mod
+
+      - name: Install golangci-lint
+        run: go install github.com/golangci/golangci-lint/cmd/golangci-lint@latest
+
+      - name: Install goimports
+        run: go install golang.org/x/tools/cmd/goimports@latest
+
+      - name: Run make check
+        run: make check