feat: support Gatsby 4.x (#219)

BREAKING CHANGE: Requires Node >=14.15.0
BREAKING CHANGE: Requires Gatsby ^4.0.0

Author: MichaelDeBoey

.github/workflows/validate.yml

@@ -16,7 +16,7 @@ jobs:
     if: ${{ !contains(github.head_ref, 'all-contributors') }}
     strategy:
       matrix:
-        node: [12.13, 12, 14, 16]
+        node: [14.15.0, 14, 16]
     runs-on: ubuntu-latest
     steps:
       - name: 🛑 Cancel Previous Runs

package.json

@@ -62,11 +62,10 @@
     "remark-html": "^13.0.2"
   },
   "peerDependencies": {
-    "gatsby": "^3.0.0"
+    "gatsby": "^4.0.0"
   },
   "engines": {
-    "node": ">=12.13.0",
-    "npm": ">=6",
-    "yarn": ">=1"
+    "node": ">=14.15.0",
+    "npm": ">=6"
   }
 }