PYTHON-3141 Add slotscheck to pre-commit checks (#890)

.pre-commit-config.yaml

@@ -34,6 +34,7 @@ repos:
   rev: 3.9.2
   hooks:
   - id: flake8
+    files: \.py$
     additional_dependencies: [
         'flake8-bugbear==20.1.4',
         'flake8-logging-format==0.6.0',
@@ -57,3 +58,11 @@ repos:
       files: ^\.github/workflows/
       types: [yaml]
       args: ["--schemafile", "https://json.schemastore.org/github-workflow"]
+
+- repo: https://github.com/ariebovenberg/slotscheck
+  rev: v0.14.0
+  hooks:
+  - id: slotscheck
+    files: \.py$
+    exclude: "^(test|tools)/"
+    stages: [manual]