chore: use the same .golangci.yml as the runner & gofumpt over gofmt (#206)

To prepare for a smooth merge in the runner codebase.

- run with --fix for gofumpt and golangci
- manual edits for
  - disabling useless package naming warning
  - rename variables that had underscore in their name
  - remove trailing else at the end of a few functions

Reviewed-on: https://code.forgejo.org/forgejo/act/pulls/206
Reviewed-by: Michael Kriese <michael.kriese@gmx.de>
Co-authored-by: Earl Warren <contact@earl-warren.org>
Co-committed-by: Earl Warren <contact@earl-warren.org>

act/common/git/git_test.go

@@ -19,7 +19,7 @@ import (
 func TestFindGitSlug(t *testing.T) {
 	assert := assert.New(t)
 
-	var slugTests = []struct {
+	slugTests := []struct {
 		url      string // input
 		provider string // expected result
 		slug     string // expected result