Update stubtest_stdlib.yml

Author: sobolevn

.github/workflows/stubtest_stdlib.yml

@@ -47,7 +47,5 @@ jobs:
           check-latest: true
       - name: Install dependencies
         run: pip install -r requirements-tests.txt
-      - name: Install mypy from git
-        run: pip install git+https://github.com/python/mypy@e8a26308d5d06925cf769b62f41ef2e4bc546ada
       - name: Run stubtest
         run: python tests/stubtest_stdlib.py