adding webbpsf data caching to GH actions

.github/workflows/roman_ci.yml

@@ -19,6 +19,25 @@ concurrency:
   cancel-in-progress: true
 
 jobs:
+  build:
+    runs-on: ubuntu-latest
+    steps:
+      - name: Cache WebbPSF data
+        id: cache-webbpsf
+        uses: actions/cache@v3
+        env:
+          cache-name: cache-webbpsf-data
+        with:
+          path: ./webbpsf-data
+          key: ${{ runner.os }}-build-${{ env.cache-name }}-${{ hashFiles('**/package-lock.json') }}
+          restore-keys: |
+            ${{ runner.os }}-build-${{ env.cache-name }}-
+            ${{ runner.os }}-build-
+            ${{ runner.os }}-
+        run: | # Get WebbPSF data files (just a subset of the full dataset!) and set up environment variable
+          wget https://stsci.box.com/shared/static/ykkvequ9cbble6qg88ldhjoep4m9ey6x.gz -O /tmp/minimal-webbpsf-data.tar.gz
+          tar -xzvf /tmp/minimal-webbpsf-data.tar.gz
+          echo "WEBBPSF_PATH=${{github.workspace}}/webbpsf-data" >> $GITHUB_ENV
   crds:
     name: retrieve current CRDS context
     runs-on: ubuntu-latest