Add source code linting for go to CI

.github/workflows/ci.yml

@@ -76,7 +76,7 @@ jobs:
                 fetch-depth: 0  # needed for :commit: docs role
 
             - name: Test for trailing whitespace
-              run: if grep -Inr '\s$' kitty kitty_tests kittens docs *.py *.asciidoc *.rst .gitattributes .gitignore; then echo Trailing whitespace found, aborting.; exit 1; fi
+              run: if grep -Inr '\s$' kitty kitty_tests kittens docs *.py *.asciidoc *.rst *.go .gitattributes .gitignore; then echo Trailing whitespace found, aborting.; exit 1; fi
 
             - name: Set up Python
               uses: actions/setup-python@v3
@@ -94,6 +94,9 @@ jobs:
             - name: Run pyflakes
               run: python -m flake8 --count .
 
+            - name: Run gofmt
+              run: unformatted=$(gofmt -s -l tools version.go); [ -n "$unformatted" ] && { echo "$unformatted"; exit 1 }
+
             - name: Build kitty package
               run: python .github/workflows/ci.py package