Use actions/setup-java v4 in doc

https://github.com/actions/setup-java/releases/tag/v4.0.0

Signed-off-by: Goooler <[email protected]>

README.md

@@ -4,7 +4,7 @@ This GitHub Action can be used to configure Gradle and optionally execute a Grad
 
 ## Why use the `gradle-build-action`?
 
-It is possible to directly invoke Gradle in your workflow, and the `actions/setup-java@v3` action provides a simple way to cache Gradle dependencies. 
+It is possible to directly invoke Gradle in your workflow, and the `actions/setup-java@v4` action provides a simple way to cache Gradle dependencies. 
 
 However, the `gradle-build-action` offers a number of advantages over this approach:
 
@@ -36,7 +36,7 @@ jobs:
     runs-on: ${{ matrix.os }}
     steps:
     - uses: actions/checkout@v4
-    - uses: actions/setup-java@v3
+    - uses: actions/setup-java@v4
       with:
         distribution: temurin
         java-version: 11
@@ -85,7 +85,7 @@ jobs:
     runs-on: ubuntu-latest
     steps:
     - uses: actions/checkout@v4
-    - uses: actions/setup-java@v3
+    - uses: actions/setup-java@v4
       with:
         distribution: temurin
         java-version: 11