add consolidation of refimage artifacts

.github/workflows/reference_tests.yml

@@ -175,3 +175,44 @@ jobs:
       - uses: codecov/codecov-action@v3
         with:
           file: lcov.info
+
+  consolidation:
+    name: Merge artifacts
+    runs-on: ubuntu-20.04
+    if: ${{ always() }} # run even if any of the three backend test jobs failed
+    needs: [cairomakie, glmakie, wglmakie]
+    steps:
+      - name: Checkout repository
+        uses: actions/checkout@v2
+        with:
+          path: 'Makie'
+      - uses: actions/download-artifact@v4
+        with:
+          name: ReferenceImages_WGLMakie
+          path: ./ReferenceImages/WGLMakie
+      - uses: actions/download-artifact@v4
+        with:
+          name: ReferenceImages_CairoMakie
+          path: ./ReferenceImages/CairoMakie
+      - uses: actions/download-artifact@v4
+        with:
+          name: ReferenceImages_GLMakie
+          path: ./ReferenceImages/GLMakie
+      - uses: julia-actions/setup-julia@v1
+        with:
+          version: '1'
+      - name: Write out major.minor version to version.txt
+        run: |
+          julia -e '
+          using TOML
+          toml_path = "Makie/Project.toml"
+          toml_data = TOML.parsefile(toml_path)
+          version = VersionNumber(toml_data["version"])
+          open("ReferenceImages/version.txt", "w") do io
+            print(io, "$(version.major).$(version.minor)")
+          end
+      - uses: actions/upload-artifact@v4
+        with:
+          name: ReferenceImages
+          path: ./ReferenceImages/
+