chore(lint): add new linters and update codebase

- add canonicalheader
- add copyloopvar
- add fatcontext
- add intrange

internal/wireguard/route_test.go

@@ -57,7 +57,6 @@ func Test_Wireguard_addRoute(t *testing.T) {
 	}
 
 	for name, testCase := range testCases {
-		testCase := testCase
 		t.Run(name, func(t *testing.T) {
 			t.Parallel()
 			ctrl := gomock.NewController(t)