golangci-lint/CI: Bump versions and introduce new linters (#798)

* golangci-lint/CI: Bump versions

Fix remaining linter issues

* Specifically set AppVeyor version

* Fix the infamous typos 👀

* Add go env cmd to AppVeyor

* Add go version cmd to AppVeyor

* Specify AppVeyor image, adjust linters

* Update go get to go install due to deprecation

* Bump golangci-lint timeout time for AppVeyor

* Change NW contract to NQ

* Address nitters

* GetRandomPair -> Pair{}

* Address nits

* Address time nitterinos plus additional tweaks

* More time inception upgrades!

* Bending time and space

common/crypto/crypto_test.go

@@ -35,9 +35,8 @@ func TestBase64Decode(t *testing.T) {
 func TestBase64Encode(t *testing.T) {
 	t.Parallel()
 	originalInput := []byte("hello")
-	expectedOutput := "aGVsbG8="
 	actualResult := Base64Encode(originalInput)
-	if actualResult != expectedOutput {
+	if expectedOutput := "aGVsbG8="; actualResult != expectedOutput {
 		t.Errorf("Expected '%s'. Actual '%s'",
 			expectedOutput, actualResult)
 	}