Upgrade to GitHub-native Dependabot (#283)

Co-authored-by: dependabot-preview[bot] <27856297+dependabot-preview[bot]@users.noreply.github.com>

.github/dependabot.yml

@@ -0,0 +1,49 @@
+version: 2
+updates:
+- package-ecosystem: cargo
+  directory: "/"
+  schedule:
+    interval: daily
+    time: "03:00"
+  open-pull-requests-limit: 10
+  ignore:
+  - dependency-name: async-trait
+    versions:
+    - 0.1.48
+    - 0.1.49
+  - dependency-name: futures-core
+    versions:
+    - 0.3.13
+    - 0.3.14
+  - dependency-name: futures-channel
+    versions:
+    - 0.3.14
+  - dependency-name: anyhow
+    versions:
+    - 1.0.40
+  - dependency-name: elliptic-curve
+    versions:
+    - 0.9.0
+    - 0.9.2
+    - 0.9.6
+  - dependency-name: pin-project
+    versions:
+    - 1.0.6
+  - dependency-name: arrayvec
+    versions:
+    - 0.6.0
+  - dependency-name: serde
+    versions:
+    - 1.0.125
+  - dependency-name: tokio
+    versions:
+    - 1.3.0
+  - dependency-name: serde_json
+    versions:
+    - 1.0.63
+  - dependency-name: ethereum-types
+    versions:
+    - 0.11.0
+  - dependency-name: yubihsm
+    versions:
+    - 0.38.0