linters: enable scopelint (#3963)

* Pin range scope vars

* Don't disable scopelint

This PR repairs linter errors seen when running the following commands:
golangci-lint run --no-config --disable-all=true --enable=scopelint

Contributes to #3262

libs/common/bytes_test.go

@@ -40,6 +40,7 @@ func TestJSONMarshal(t *testing.T) {
 	}
 
 	for i, tc := range cases {
+		tc := tc
 		t.Run(fmt.Sprintf("Case %d", i), func(t *testing.T) {
 			ts := TestStruct{B1: tc.input, B2: tc.input}