build: recommend Python 3.8 to build on Windows

PR-URL: #34182
Reviewed-By: Christian Clauss <cclauss@me.com>
Reviewed-By: Luigi Pinca <luigipinca@gmail.com>
Reviewed-By: Tobias Nießen <tniessen@tnie.de>
Reviewed-By: James M Snell <jasnell@gmail.com>
Reviewed-By: Jiawen Geng <technicalcute@gmail.com>

.github/workflows/build-tarball.yml

@@ -72,10 +72,10 @@ jobs:
         run: |
           git config --global core.autocrlf true
       - uses: actions/checkout@v2
-      - name: Set up Python 2.7
-        uses: actions/setup-python@v1
+      - name: Set up Python 3.8
+        uses: actions/setup-python@v2
         with:
-          python-version: 2.7
+          python-version: 3.8
       - name: Environment Information
         run: npx envinfo
       - name: Download tarball

BUILDING.md

@@ -526,7 +526,7 @@ to run it again before invoking `make -j4`.
 
 ##### Option 1: Manual install
 
-* [Python 2.7](https://www.python.org/downloads/)
+* [Python 3.8](https://www.python.org/downloads/)
 * The "Desktop development with C++" workload from
   [Visual Studio 2017 or 2019](https://visualstudio.microsoft.com/downloads/) or
   the "Visual C++ build tools" workload from the