chore[ci]: merge mypy job into lint (vyperlang#3840)

reduce the number of jobs, since mypy really belongs in the lint job
anyways.

.github/workflows/test.yml

@@ -35,6 +35,9 @@ jobs:
     - name: Run isort
       run: isort --check-only --diff ./vyper ./tests ./setup.py
 
+    - name: Run mypy
+      run: make mypy
+
   docs:
     runs-on: ubuntu-latest
 
@@ -53,24 +56,6 @@ jobs:
       - name: Run Tox
         run: TOXENV=docs tox -r
 
-  mypy:
-    runs-on: ubuntu-latest
-
-    steps:
-    - uses: actions/checkout@v4
-
-    - name: Set up Python 3.11
-      uses: actions/setup-python@v5
-      with:
-        python-version: "3.11"
-        cache: "pip"
-
-    - name: Install Dependencies
-      run: pip install .[lint]
-
-    - name: Run mypy
-      run: make mypy
-
   # "Regular"/core tests.
   tests:
     runs-on: ubuntu-latest