Remove seed-isort-config pre-commit hook

As of isort >=5, which we use, the seed-isort-config hook has been deprecated,
and the repository archived. I have removed the hook and the configuration
options it updated as a result.

.isort.cfg

@@ -6,10 +6,5 @@ import_heading_stdlib=Standard Python Libraries
 import_heading_thirdparty=Third-Party Libraries
 import_heading_firstparty=cisagov Libraries
 
-# Should be auto-populated by seed-isort-config hook
-known_third_party=
-# These must be manually set to correctly separate them from third party libraries
-known_first_party=
-
 # Run isort under the black profile to align with our other Python linting
 profile=black

.pre-commit-config.yaml

@@ -60,10 +60,6 @@ repos:
     rev: 20.8b1
     hooks:
       - id: black
-  - repo: https://github.com/asottile/seed-isort-config
-    rev: v2.2.0
-    hooks:
-      - id: seed-isort-config
   - repo: https://github.com/timothycrosley/isort
     rev: 5.5.0
     hooks: