Fixed: Database type when PG host contains ".db" (#4435)

Previously was looking for a ".db" in the connection string, which is
the typical sqlite filename. The problem is if your connection string has a
.db anywhere in it, such as postgres.db.internal it'll think its a
sqlite file

Solution borrowed from sonarr:

https://github.com/Sonarr/Sonarr/blob/develop/src/NzbDrone.Core/Datastore/Database.cs#L43

src/NzbDrone.Core/Datastore/Database.cs

@@ -1,5 +1,6 @@
-using System;
+using System;
 using System.Data;
+using System.Data.SQLite;
 using System.Text.RegularExpressions;
 using Dapper;
 using NLog;
@@ -40,14 +41,7 @@ namespace NzbDrone.Core.Datastore
             {
                 using (var db = _datamapperFactory())
                 {
-                    if (db.ConnectionString.Contains(".db"))
-                    {
-                        return DatabaseType.SQLite;
-                    }
-                    else
-                    {
-                        return DatabaseType.PostgreSQL;
-                    }
+                    return db is SQLiteConnection ? DatabaseType.SQLite : DatabaseType.PostgreSQL;
                 }
             }
         }