Run mypy as part of the lint.sh script. (#8633)

CONTRIBUTING.md

@@ -46,7 +46,7 @@ locally. You'll need python 3.6 or later, and to install a number of tools:
 
 ```
 # Install the dependencies
-pip install -e ".[lint]"
+pip install -e ".[lint,mypy]"
 
 # Run the linter script
 ./scripts-dev/lint.sh
@@ -63,7 +63,7 @@ run-time:
 ./scripts-dev/lint.sh path/to/file1.py path/to/file2.py path/to/folder
 ```
 
-You can also provided the `-d` option, which will lint the files that have been
+You can also provide the `-d` option, which will lint the files that have been
 changed since the last git commit. This will often be significantly faster than
 linting the whole codebase.
 

changelog.d/8633.misc

@@ -0,0 +1 @@
+Run `mypy` as part of the lint.sh script.

scripts-dev/lint.sh

@@ -94,3 +94,4 @@ isort "${files[@]}"
 python3 -m black "${files[@]}"
 ./scripts-dev/config-lint.sh
 flake8 "${files[@]}"
+mypy