Fix Windows python3 path (#93387)

If a Windows runner is re-used, python3 should have already been setup.  We will just need to make it available in `GITHUB_PATH`, so subsequent actions can use it
Pull Request resolved: https://github.com/pytorch/pytorch/pull/93387
Approved by: https://github.com/clee2000, https://github.com/malfet, https://github.com/seemethere
diff --git a/.github/actions/setup-win/action.yml b/.github/actions/setup-win/action.yml
index e1b17a3..8453781 100644
--- a/.github/actions/setup-win/action.yml
+++ b/.github/actions/setup-win/action.yml
@@ -59,7 +59,9 @@
 
         if [[ "${EXIT_CODE}" == "0" ]]; then
           echo "Found Python3 at ${PYTHON3}, adding it into GITHUB_PATH"
-          echo "${PYTHON3}" >> "${GITHUB_PATH}"
+
+          PYTHON_PATH=$(dirname "${PYTHON3}")
+          echo "${PYTHON_PATH}" >> "${GITHUB_PATH}"
         else
           # According to https://docs.conda.io/en/latest/miniconda.html, we are using the Miniconda3
           # installation, which is Python 3 based. Its Python is default to Python 3. Further, there