Rework environment variable handling in mpw_precheck github action

.github/workflows/microwatt_tapeout_ci.yml

diff --git a/.github/workflows/microwatt_tapeout_ci.yml b/.github/workflows/microwatt_tapeout_ci.yml
index cc71364..c6b38f2 100644
--- a/.github/workflows/microwatt_tapeout_ci.yml
+++ b/.github/workflows/microwatt_tapeout_ci.yml
@@ -15,19 +15,26 @@
   mpw_precheck:
     timeout-minutes: 720
     runs-on: ubuntu-22.04
+
+    env:
+          PDK: sky130B
+          #PDK_ROOT: /home/runner/work/pdk
+          #OPENLANE_ROOT: /home/runner/work/caravel_user_project/openlane
+          PDK_ROOT: ${{ github.workspace }}/pdk
+          PDKPATH: ${{ github.workspace }}/pdk/sky130B
+          OPENLANE_ROOT: ${{ github.workspace }}/openlane
+          INPUT_DIRECTORY: ${{ github.workspace }}
+          PRECHECK_ROOT: ${{ github.workspace }}/mpw_precheck
+          OUTPUT_DIRECTORY: ${{ github.workspace }}/mpw_precheck_result
+          OUTPUT: ${{ github.workspace }}/mpw_precheck_result/logs/precheck.log
+
     steps:
       - uses: actions/checkout@v2
 
-      - name: Create environment variables
-        run: |
-          echo "PDK=sky130B" >> $GITHUB_ENV
-          echo "PDK_ROOT=/home/runner/work/pdk" >> $GITHUB_ENV
-          echo "OPENLANE_ROOT=/home/runner/work/caravel_user_project/openlane" >> $GITHUB_ENV
-
       - name: Install dependencies
         run: |
-          sudo mkdir -p ${{ env.PDK_ROOT }}
-          sudo chown -R $USER:$USER ${{ env.PDK_ROOT }}
+          sudo mkdir -p $PDK_ROOT
+          sudo chown -R $USER:$USER $PDK_ROOT
           make install
           make openlane
           make pdk-with-volare
@@ -35,15 +42,9 @@
 
       - name: Run MPW-Precheck
         run: |
-          export INPUT_DIRECTORY=$(pwd)
-          export PRECHECK_ROOT=$INPUT_DIRECTORY/mpw_precheck
-          export OUTPUT_DIRECTORY=$INPUT_DIRECTORY/mpw_precheck_result
-          export OUTPUT=$OUTPUT_DIRECTORY/logs/precheck.log
-          export PDKPATH=$PDK_ROOT/sky130B
-
           git clone --depth=1 -b mpw-7a https://github.com/efabless/mpw_precheck.git
 
-          docker run -v "$PRECHECK_ROOT":"$PRECHECK_ROOT" -v "$INPUT_DIRECTORY":"$INPUT_DIRECTORY" -v "${{ env.PDK_ROOT }}":"${{ env.PDK_ROOT }}" -e INPUT_DIRECTORY="$INPUT_DIRECTORY" -e PDK_ROOT="${{ env.PDK_ROOT }}" -e PDKPATH="${{ env.PDKPATH }}" -u $(id -u "$USER"):$(id -g "$USER") efabless/mpw_precheck:latest bash -c "cd $PRECHECK_ROOT; python3 mpw_precheck.py --input_directory $INPUT_DIRECTORY --pdk_path ${{ env.PDKPATH }} --output_directory $OUTPUT_DIRECTORY license makefile consistency xor magic_drc klayout_beol klayout_feol klayout_met_min_ca_density klayout_offgrid klayout_pin_label_purposes_overlapping_drawing klayout_zeroarea"
+          docker run -v "$PRECHECK_ROOT":"$PRECHECK_ROOT" -v "$INPUT_DIRECTORY":"$INPUT_DIRECTORY" -v "$PDK_ROOT":"$PDK_ROOT" -e INPUT_DIRECTORY="$INPUT_DIRECTORY" -e PDK_ROOT="$PDK_ROOT" -e PDKPATH="$PDKPATH" -u $(id -u "$USER"):$(id -g "$USER") efabless/mpw_precheck:latest bash -c "cd $PRECHECK_ROOT; python3 mpw_precheck.py --input_directory $INPUT_DIRECTORY --pdk_path $PDKPATH --output_directory $OUTPUT_DIRECTORY license makefile consistency xor magic_drc klayout_beol klayout_feol klayout_met_min_ca_density klayout_offgrid klayout_pin_label_purposes_overlapping_drawing klayout_zeroarea"
 
           cnt=$(grep -c "All Checks Passed" "$OUTPUT")
           if ! [[ $cnt ]]; then cnt=0; fi