Add basic CI

.github/workflows/ExportPluto.yaml

@@ -5,11 +5,12 @@ on:
   push:
     branches:
       - master
+  pull_request:
 
 # When two jobs run in parallel, cancel the older ones, to make sure that the
 # website is generated from the most recent commit.
 concurrency:
-    group: pluto-export
+    group: pluto-export-${{ github.ref }}
     cancel-in-progress: true
 
 # This action needs permission to write the exported HTML file to the gh-pages branch.
@@ -30,16 +31,18 @@ jobs:
                   version: "1" # This will automatically pick the latest Julia version
 
             - name: Cache Julia artifacts & such
-              uses: julia-actions/cache@v1
+              uses: julia-actions/cache@v2
               with:
-                cache-registries: "true"
+                # Contains the node env for PlutoPDF.
+                # Disable so it installs Chromium every time.
+                cache-scratchspaces: false
 
             # We set up a folder that Pluto can use to cache exported
             # notebooks. If the notebook file did not change, then Pluto can
             # take the exported file from cache instead of running the
             # notebook.
             - name: Set up notebook state cache
-              uses: actions/cache@v3
+              uses: actions/cache@v4
               with:
                   path: pluto_state_cache
                   key: ${{ runner.os }}-pluto_state_cache-v2-${{ hashFiles('**/Project.toml', '**/Manifest.toml', '.github/workflows/*' ) }}-${{ hashFiles('**/*jl') }}
@@ -74,8 +77,8 @@ jobs:
                   end
                   '
 
-
             - name: Deploy to gh-pages
+              if: github.event_name == 'push' && github.ref == 'refs/heads/master'
               uses: JamesIves/github-pages-deploy-action@releases/v4
               with:
                   token: ${{ secrets.GITHUB_TOKEN }}