Update cache action

Author: nealfennimore

.github/workflows/docs.yml

@@ -22,7 +22,7 @@ jobs:
         cache: 'npm'
 
     - name: Retrieve the cached "node_modules" directory (if present)
-      uses: actions/cache@v2
+      uses: actions/cache@v4
       id: node-cache
       with:
        path: node_modules

.github/workflows/publish.yml

@@ -23,7 +23,7 @@ jobs:
         cache: 'npm'
 
     - name: Retrieve the cached "node_modules" directory (if present)
-      uses: actions/cache@v2
+      uses: actions/cache@v4
       id: node-cache
       with:
        path: node_modules

.github/workflows/test.yml

@@ -23,7 +23,7 @@ jobs:
         cache: 'npm'
 
     - name: Retrieve the cached "node_modules" directory (if present)
-      uses: actions/cache@v2
+      uses: actions/cache@v4
       id: node-cache
       with:
        path: node_modules