chore(lint): add new linters and update codebase

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

internal/wireguard/settings_test.go

@@ -64,7 +64,6 @@ func Test_Settings_SetDefaults(t *testing.T) {
 	}
 
 	for name, testCase := range testCases {
-		testCase := testCase
 		t.Run(name, func(t *testing.T) {
 			t.Parallel()
 
@@ -293,7 +292,6 @@ func Test_Settings_Check(t *testing.T) {
 	}
 
 	for name, testCase := range testCases {
-		testCase := testCase
 		t.Run(name, func(t *testing.T) {
 			t.Parallel()
 
@@ -434,7 +432,6 @@ func Test_Settings_Lines(t *testing.T) {
 	}
 
 	for name, testCase := range testCases {
-		testCase := testCase
 		t.Run(name, func(t *testing.T) {
 			t.Parallel()