simplify CI to docker build only (refs #130)

The Dockerfile already runs make check, so the CI action only needs
to run docker build. Remove go setup, linter installation, and
direct make check invocation from the workflow.

.gitea/workflows/check.yml

@@ -10,17 +10,7 @@ jobs:
   check:
     runs-on: ubuntu-latest
     steps:
-      - uses: actions/checkout@34e114876b0b11c390a56381ad16ebd13914f8d5 # v4
+      - uses: actions/checkout@34e114876b0b11c390a56381ad16ebd13914f8d5 # v4, 2024-10-13
 
-      - uses: actions/setup-go@40f1582b2485089dde7abd97c1529aa768e1baff # v5
-        with:
-          go-version-file: go.mod
-
-      - name: Install golangci-lint
-        run: go install github.com/golangci/golangci-lint/v2/cmd/golangci-lint@5d1e709b7be35cb2025444e19de266b056b7b7ee # v2.10.1
-
-      - name: Install goimports
-        run: go install golang.org/x/tools/cmd/goimports@009367f5c17a8d4c45a961a3a509277190a9a6f0 # v0.42.0
-
-      - name: Run make check
-        run: make check
+      - name: Build (runs make check inside Dockerfile)
+        run: docker build .