fix pip conflict

Author: morganchen12

.github/workflows/android.yml

@@ -115,6 +115,8 @@ jobs:
       - name: Install prerequisites
         shell: bash
         run: |
+          # System pip conflicts with pip install invoked by prereqs script
+          sudo apt-get remove pip
           build_scripts/android/install_prereqs.sh
           echo "NDK_ROOT=/tmp/android-ndk-r21e" >> $GITHUB_ENV
           echo "ANDROID_NDK_HOME=/tmp/android-ndk-r21e" >> $GITHUB_ENV