Enable stricter linting with golangci-lint (#316)

* update golangci-lint

* add golangci config file w/ more linters

* correct issues flagged by stricter linters

* add more generous timeout for golangci-lint

* add some style + formatting guidelines

* move timeout to config file

* go fmt

internal/api/security/useragentblock.go

@@ -31,8 +31,7 @@ func (m *Module) UserAgentBlock(c *gin.Context) {
 		"func": "UserAgentBlock",
 	})
 
-	ua := c.Request.UserAgent()
-	if ua == "" {
+	if ua := c.Request.UserAgent(); ua == "" {
 		l.Debug("aborting request because there's no user-agent set")
 		c.AbortWithStatus(http.StatusTeapot)
 		return