set indexes on gene columns

Try to improve queries

• Setting indexes

backend/metagenedb/apps/catalog/migrations/0028_index_source_and_functions.py

+# Generated by Django 3.1.7 on 2021-03-26 13:48
+
+from django.db import migrations, models
+
+
+class Migration(migrations.Migration):
+
+    dependencies = [
+        ('catalog', '0027_fix_deprecated_jsonfield'),
+    ]
+
+    operations = [
+        migrations.AlterField(
+            model_name='gene',
+            name='functions',
+            field=models.ManyToManyField(db_index=True, through='catalog.GeneFunction', to='catalog.Function'),
+        ),
+        migrations.AlterField(
+            model_name='gene',
+            name='source',
+            field=models.CharField(choices=[('undef', 'Undefined'), ('igc', 'IGC'), ('virgo', 'Virgo')], db_index=True, default='undef', max_length=10),
+        ),
+    ]