upgrade to non-deprecated version of actions/cache

Author: timkim

.github/workflows/deploy.yml

@@ -114,7 +114,7 @@ jobs:
           cmd: install
 
       - name: Gatsby Cache
-        uses: actions/cache@v2
+        uses: actions/cache@v3
         with:
           path: |
             public
@@ -218,7 +218,7 @@ jobs:
           cmd: install
 
       - name: Gatsby Cache
-        uses: actions/cache@v2
+        uses: actions/cache@v3
         with:
           path: |
             public