Fix DB errors when using MySQL/MariaDB.

Fixes #69.

django_etebase/migrations/0037_auto_20210127_1237.py

@@ -0,0 +1,18 @@
+# Generated by Django 3.1.1 on 2021-01-27 12:37
+
+from django.db import migrations, models
+
+
+class Migration(migrations.Migration):
+
+    dependencies = [
+        ('django_etebase', '0036_auto_20201214_1128'),
+    ]
+
+    operations = [
+        migrations.AlterField(
+            model_name='collectiontype',
+            name='uid',
+            field=models.BinaryField(db_index=True, editable=True, max_length=1024, unique=True),
+        ),
+    ]