ci: use LF line ending always in the case of *.go files

gofmt formats all CRLF to LF in *.go files.
it results failure of convention job on GitHub Actions,
especially on windows host runners.

.gitattributes

@@ -0,0 +1 @@
+*.go text eol=lf

.github/workflows/go.yml

@@ -15,6 +15,9 @@ jobs:
     with:
       run: |
         make convention
+        echo '====='
+        gofmt -d .
+        echo '====='
         # TODO: use gofmt linter
         test "$(gofmt -l . | wc -l)" -eq 0
   test:

.gitignore

@@ -2,6 +2,7 @@
 !.circleci
 !.dependabot
 !.github
+!.gitattributes
 !.gitignore
 !.goxc.json
 !.travis.yml