[#1266] .forgejo: Add gofumpt action

`gofumpt` was skipped by pre-commit on CI, and now is used
in a separate action.

Signed-off-by: Ekaterina Lebedeva <ekaterina.lebedeva@yadro.com>

.forgejo/workflows/tests.yml

@@ -89,3 +89,21 @@ jobs:
 
       - name: Run gopls
         run: make gopls-run
+
+  fumpt:
+    name: Run gofumpt
+    runs-on: ubuntu-latest
+    steps:
+      - uses: actions/checkout@v3
+
+      - name: Set up Go
+        uses: actions/setup-go@v3
+        with:
+          go-version: '1.22'
+          cache: true
+
+      - name: Install gofumpt
+        run: make fumpt-install
+
+      - name: Run gofumpt
+        run: make fumpt