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

engine/database_connection.go

@@ -51,8 +51,7 @@ func SetupDatabaseConnectionManager(cfg *database.Config) (*DatabaseConnectionMa
 		cfg:      *cfg,
 		dbConn:   database.DB,
 	}
-	err := m.dbConn.SetConfig(cfg)
-	if err != nil {
+	if err := m.dbConn.SetConfig(cfg); err != nil {
 		return nil, err
 	}
 
@@ -177,8 +176,7 @@ func (m *DatabaseConnectionManager) checkConnection() error {
 		return database.ErrNoDatabaseProvided
 	}
 
-	err := m.dbConn.Ping()
-	if err != nil {
+	if err := m.dbConn.Ping(); err != nil {
 		m.dbConn.SetConnected(false)
 		return err
 	}