[chore] Update Go version to 1.18 (#444)

* linting with new golangci-lint version

* update go to 1.18

* bump versions in drone.yml

* use new runtime/debug package for version info

* remove Commit build flag from goreleaser

* remove mock commit + version from build script

* go fmt

* add dummy version env flag to test container

* install git in golang container for testing

* only set versionString if Version is defined

internal/db/bundb/mention.go

@@ -46,7 +46,13 @@ func (m *mentionDB) getMentionCached(id string) (*gtsmodel.Mention, bool) {
 	if !ok {
 		return nil, false
 	}
-	return v.(*gtsmodel.Mention), true
+
+	mention, ok := v.(*gtsmodel.Mention)
+	if !ok {
+		panic("mention cache entry was not a mention")
+	}
+
+	return mention, true
 }
 
 func (m *mentionDB) putMentionCache(mention *gtsmodel.Mention) {

internal/db/bundb/notification.go

@@ -114,7 +114,13 @@ func (n *notificationDB) getNotificationCache(id string) (*gtsmodel.Notification
 	if !ok {
 		return nil, false
 	}
-	return v.(*gtsmodel.Notification), true
+
+	notif, ok := v.(*gtsmodel.Notification)
+	if !ok {
+		panic("notification cache entry was not a notification")
+	}
+
+	return notif, true
 }
 
 func (n *notificationDB) putNotificationCache(notif *gtsmodel.Notification) {