Adding mypy to dep list and clarifying Stubs stage name

Author: sw23

.github/workflows/build.yml

@@ -37,7 +37,7 @@ jobs:
       run: |
         sudo apt-get install -y eatmydata
         sudo eatmydata apt-get install -y gettext librsvg2-bin mingw-w64 latexmk texlive-fonts-recommended texlive-latex-recommended texlive-latex-extra
-        pip install requests sh click setuptools cpp-coveralls "Sphinx<4" sphinx-rtd-theme recommonmark sphinx-autoapi sphinxcontrib-svg2pdfconverter polib pyyaml astroid isort black awscli
+        pip install requests sh click setuptools cpp-coveralls "Sphinx<4" sphinx-rtd-theme recommonmark sphinx-autoapi sphinxcontrib-svg2pdfconverter polib pyyaml astroid isort black awscli mypy
     - name: Versions
       run: |
         gcc --version
@@ -67,7 +67,7 @@ jobs:
     - name: mpy Tests
       run: MICROPY_CPYTHON3=python3.8 MICROPY_MICROPYTHON=../ports/unix/micropython_coverage ./run-tests -j1 --via-mpy -d basics float
       working-directory: tests
-    - name: Stubs
+    - name: Build and Validate Stubs
       run: make check-stubs -j2
     - uses: actions/upload-artifact@v2
       with: