Fix `dependabot.yml`

Signed-off-by: George Jenkins <gvjenkins@gmail.com>

.github/dependabot.yml

@@ -3,7 +3,7 @@ version: 2
 updates:
   - # Keep dev-v3 branch dependencies up to date, while Helm v3 is within support
     package-ecosystem: "gomod"
-    target_branch: "dev-v3"
+    target-branch: "dev-v3"
     directory: "/"
     schedule:
       interval: "daily"
@@ -18,7 +18,7 @@ updates:
           - "k8s.io/client-go"
           - "k8s.io/kubectl"
   - package-ecosystem: "gomod"
-    target_branch: "main"
+    target-branch: "main"
     directory: "/"
     schedule:
       interval: "daily"
@@ -33,7 +33,7 @@ updates:
           - "k8s.io/client-go"
           - "k8s.io/kubectl"
   - package-ecosystem: "github-actions"
-    target_branch: "main"
+    target-branch: "main"
     directory: "/"
     schedule:
       interval: "daily"