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

tests/unit/test_sql_analyser.py

@@ -19,10 +19,10 @@ class SqlAnalyserTestCase(unittest.TestCase):
 
     def assertValidSql(self, sql, allow_warnings=False):
         errors, _, warnings = self.analyse_sql(sql)
-        self.assertEqual(0, len(errors), "Found errors in sql: {}".format(errors))
+        self.assertEqual(0, len(errors), f"Found errors in sql: {errors}")
         if not allow_warnings:
             self.assertEqual(
-                0, len(warnings), "Found warnings in sql: {}".format(errors)
+                0, len(warnings), f"Found warnings in sql: {errors}"
             )
 
     def assertBackwardIncompatibleSql(self, sql, code=None):