[ci] Upgrade pip on MSVC job

To avoid bad pre-installed version.

.github/workflows/msvc-ci.yml

@@ -30,6 +30,9 @@ jobs:
       - uses: ilammy/msvc-dev-cmd@v1
         with:
           arch : ${{ matrix.ARCH }}
+      - name: Upgrade pip
+        run: |
+          python -m pip install -U pip
       - name: Install Dependencies
         run: |
           pip install --upgrade meson ninja fonttools