Update Black's target-version to py37

<!-- Provide a general summary of your proposed changes in the Title field above -->

### Description
<!-- Describe your changes in detail -->

Black's `target-version` was still set to `['py27', 'py36']`. Set it to `[py37]` instead.

Also update Black and other pre-commit hooks and re-format with Black.

### Checklist
<!-- go over following points. check them with an `x` if they do apply, (they turn into clickable checkboxes once the PR is submitted, so no need to do everything at once)

-->

This pull request is:

- [ ] A documentation / typographical error fix
	- Good to go, no issue or tests are needed
- [ ] A short code fix
	- please include the issue number, and create an issue if none exists, which
	  must include a complete example of the issue.  one line code fixes without an
	  issue and demonstration will not be accepted.
	- Please include: `Fixes: #<issue number>` in the commit message
	- please include tests.   one line code fixes without tests will not be accepted.
- [ ] A new feature implementation
	- please include the issue number, and create an issue if none exists, which must
	  include a complete example of how the feature would look.
	- Please include: `Fixes: #<issue number>` in the commit message
	- please include tests.

**Have a nice day!**

Closes: #7536
Pull-request: https://github.com/sqlalchemy/sqlalchemy/pull/7536
Pull-request-sha: b3aedf5570d7e0ba6c354e5989835260d0591b08

Change-Id: I8be85636fd2c9449b07a8626050c8bd35bd119d5

1 files changed, 2 insertions, 2 deletions

diff --git a/lib/sqlalchemy/dialects/postgresql/ext.py b/lib/sqlalchemy/dialects/postgresql/ext.py
index e323da8be..1eabed403 100644
--- a/lib/sqlalchemy/dialects/postgresql/ext.py
+++ b/lib/sqlalchemy/dialects/postgresql/ext.py
@@ -221,7 +221,7 @@ class ExcludeConstraint(ColumnCollectionConstraint):
             *columns,
             name=kw.get("name"),
             deferrable=kw.get("deferrable"),
-            initially=kw.get("initially")
+            initially=kw.get("initially"),
         )
         self.using = kw.get("using", "gist")
         where = kw.get("where")
@@ -258,7 +258,7 @@ class ExcludeConstraint(ColumnCollectionConstraint):
             deferrable=self.deferrable,
             initially=self.initially,
             where=self.where,
-            using=self.using
+            using=self.using,
         )
         c.dispatch._update(self.dispatch)
         return c