chore: Upgrade Python syntax with pyupgrade

Run with the following pre-commit configuration:

```
repos:
  - repo: https://github.com/asottile/pyupgrade
    rev: v3.1.0
    hooks:
      - id: pyupgrade
        args: [ "--py3-plus", "--py36-plus", "--py37-plus" ]
```

The rationale for every change can be found at https://github.com/asottile/pyupgrade

django_migration_linter/management/commands/lintmigrations.py

@@ -19,7 +19,7 @@ from ..utils import (
 CONFIG_NAME = "django_migration_linter"
 PYPROJECT_TOML = "pyproject.toml"
 DEFAULT_CONFIG_FILES = (
-    ".{}.cfg".format(CONFIG_NAME),
+    f".{CONFIG_NAME}.cfg",
     "setup.cfg",
     "tox.ini",
 )

django_migration_linter/management/commands/makemigrations.py

@@ -34,7 +34,7 @@ class Command(MakeMigrationsCommand):
     help = "Creates new migration(s) for apps and lints them."
 
     def add_arguments(self, parser):
-        super(Command, self).add_arguments(parser)
+        super().add_arguments(parser)
         parser.add_argument(
             "--lint",
             action="store_true",
@@ -49,10 +49,10 @@ class Command(MakeMigrationsCommand):
         self.warnings_as_errors = options["warnings_as_errors"]
         self.sql_analyser = options["sql_analyser"]
         configure_logging(options["verbosity"])
-        return super(Command, self).handle(*app_labels, **options)
+        return super().handle(*app_labels, **options)
 
     def write_migration_files(self, changes):
-        super(Command, self).write_migration_files(changes)
+        super().write_migration_files(changes)
 
         if (
             not getattr(settings, "MIGRATION_LINTER_OVERRIDE_MAKEMIGRATIONS", False)