Refactor Dependabot configuration for NuGet and devcontainers updates (#615)

Enhance the Dependabot configuration by specifying target branches for NuGet and devcontainers updates, ensuring a more structured update process.

Author: michael-j-green

.github/dependabot.yml

@@ -5,11 +5,23 @@
 
 version: 2
 updates:
-  - package-ecosystem: "nuget" # See documentation for possible values
-    directory: "/" # Location of package manifests
+  - package-ecosystem: "nuget"
+    directory: "/"
+    schedule:
+      interval: "weekly"
+    target-branch: "main"
+  - package-ecosystem: "nuget"
+    directory: "/"
+    schedule:
+      interval: "weekly"
+    target-branch: "branch-v1.7.0"
+  - package-ecosystem: "devcontainers"
+    directory: "/"
     schedule:
       interval: "weekly"
+    target-branch: "main"
   - package-ecosystem: "devcontainers"
     directory: "/"
     schedule:
       interval: "weekly"
+    target-branch: "branch-v1.7.0"