Increase the open-pull-requests-limit.

By default, dependabot opens a maximum of five pull requests for version updates. Once there are five open pull requests from dependabot, dependabot will not open any new requests until some of those open requests are merged or closed.
With this change, dependabot can open up to 10 pull requests.

.github/dependabot.yml

@@ -23,30 +23,35 @@ updates:
       interval: "weekly"
     commit-message:
       prefix: "MINOR: [CI] "
+    open-pull-requests-limit: 10
   - package-ecosystem: "gomod"
     directory: "/go/"
     schedule:
       interval: "weekly"
     commit-message:
       prefix: "MINOR: [Go] "
+    open-pull-requests-limit: 10
   - package-ecosystem: "maven"
     directory: "/java/"
     schedule:
       interval: "weekly"
     commit-message:
       prefix: "MINOR: [Java] "
+    open-pull-requests-limit: 10
   - package-ecosystem: "npm"
     directory: "/js/"
     schedule:
       interval: "monthly"
     commit-message:
       prefix: "MINOR: [JS] "
+    open-pull-requests-limit: 10
   - package-ecosystem: "nuget"
     directory: "/csharp/"
     schedule:
       interval: "weekly"
     commit-message:
       prefix: "MINOR: [C#] "
+    open-pull-requests-limit: 10
     ignore:
       - dependency-name: "Microsoft.Extensions.*"
         update-types: