ci-artifacts: revert to building git-for-windows/git for now

Upstream Git is not ready yet to build on Windows/ARM64. Only once
gitgitgadget/git#1904 will trickle down to
upstream's default branch will that be the case.

Signed-off-by: Johannes Schindelin <[email protected]>

Author: dscho

.github/workflows/ci-artifacts.yml

@@ -43,9 +43,9 @@ jobs:
         with:
           name: minimal-sdk
           path: artifacts/git-sdk-aarch64-minimal.tar.gz
-      - name: clone git.git's `master`
-        run: git clone --depth=1 --branch master https://github.com/git/git ..\git
-      - name: build current `master` of git.git
+      - name: clone git-for-windows/git's `main`
+        run: git clone --depth=1 --branch main https://github.com/git-for-windows/git ..\git
+      - name: build current `main` of git-for-windows/git
         shell: bash
         run: |
           set -x