Add Dependabot (#4069)

Author: daxpedda

.github/dependabot.yaml

@@ -0,0 +1,20 @@
+version: 2
+
+updates:
+  - package-ecosystem: cargo
+    directory: /
+    schedule:
+      interval: daily
+    ignore:
+      - dependency-name: 'wasmparser'
+      - dependency-name: 'wasmprinter'
+      - dependency-name: 'wast'
+
+  - package-ecosystem: github-actions
+    directory: /
+    schedule:
+      interval: daily
+    groups:
+      github-actions:
+        patterns:
+          - "*"