Update test pipeline with carsus regression data

.github/actions/setup_lfs/action.yml

@@ -0,0 +1,52 @@
+name: "Setup LFS"
+description: "Pull LFS repositories and caches them"
+
+
+inputs:
+  regression-data-repo:
+    description: "carsus regression data repository"
+    required: false
+    default: "tardis-sn/carsus-regression-data"
+
+runs:
+  using: "composite"
+  steps:
+    - name: Clone tardis-sn/carsus-regression-data
+      uses: actions/checkout@v4
+      with:
+        repository: ${{ inputs.regression-data-repo }}
+        path: carsus-regression-data
+
+    - name: Create LFS file list
+      run: git lfs ls-files -l | cut -d' ' -f1 | sort > .lfs-assets-id
+      working-directory: carsus-regression-data
+      shell: bash
+
+    - name: Restore LFS cache
+      uses: actions/cache/restore@v4
+      id: lfs-cache-regression-data
+      with:
+        path: carsus-regression-data/.git/lfs
+        key: ${{ runner.os }}-lfs-${{ hashFiles('carsus-regression-data/.lfs-assets-id') }}-v1
+
+    - name: Git LFS Pull
+      run: git lfs pull
+      working-directory: carsus-regression-data
+      if: steps.lfs-cache-regression-data.outputs.cache-hit != 'true'
+      shell: bash
+
+    - name: Git LFS Checkout
+      run: git lfs checkout
+      working-directory: carsus-regression-data
+      if: steps.lfs-cache-regression-data.outputs.cache-hit == 'true'
+      shell: bash
+
+    - name: Save LFS cache if not found
+      # uses fake ternary
+      # for reference: https://github.com/orgs/community/discussions/26738#discussioncomment-3253176
+      if: ${{ steps.lfs-cache-regression-data.outputs.cache-hit != 'true' && !contains(github.ref, 'merge') && always() || false }}
+      uses: actions/cache/save@v4
+      id: lfs-cache-regression-data-save
+      with:
+        path: carsus-regression-data/.git/lfs
+        key: ${{ runner.os }}-lfs-${{ hashFiles('carsus-regression-data/.lfs-assets-id') }}-v1

.github/workflows/tests.yml

@@ -27,7 +27,7 @@ env:
   CHIANTI_DL_URL: https://download.chiantidatabase.org
   CHIANTI_DB_VER: CHIANTI_v9.0.1_database.tar.gz
   PYTEST_FLAGS: --remote-data --refdata=carsus-refdata
-                --cov=carsus --cov-report=xml --cov-report=html   
+                --cov=carsus --cov-report=xml --cov-report=html  --carsus-regression-data=${{ github.workspace }}/carsus-regression-data
   NBCONVERT_CMD: jupyter nbconvert --execute --ExecutePreprocessor.timeout=600 --to html
   CODECOV_TOKEN: ${{ secrets.CODECOV_TOKEN }}
   CMFGEN_DL_URL: http://kookaburra.phyast.pitt.edu/hillier/cmfgen_files
@@ -51,6 +51,9 @@ jobs:
     steps:
       - uses: actions/checkout@v4
 
+      - name: Setup LFS
+        uses: ./.github/actions/setup_lfs
+
       - name: Clone tardis-sn/carsus-refdata
         uses: actions/checkout@v4
         with: