chore(deps): update Spring Boot to 4.1.0 and Gradle wrapper to 9.6.1

Also bump ravsamhq/notify-slack-action from v1 to v2; v1's Docker
action fails in GitHub Actions with a Python TypeError.

Recreates #89 under dex-the-ai.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

Author: dex-the-ai

.github/workflows/tests.yaml

@@ -57,7 +57,7 @@ jobs:
 
       - name: Report Status
         if: always()
-        uses: ravsamhq/notify-slack-action@v1
+        uses: ravsamhq/notify-slack-action@v2
         with:
           status: ${{ job.status }}
           notify_when: "failure"

build.gradle

@@ -1,5 +1,5 @@
 plugins {
-	id 'org.springframework.boot' version '4.0.6'
+	id 'org.springframework.boot' version '4.1.0'
 	id 'io.spring.dependency-management' version '1.1.7'
 	id 'java'
 }

gradle/wrapper/gradle-wrapper.properties

@@ -1,6 +1,6 @@
 distributionBase=GRADLE_USER_HOME
 distributionPath=wrapper/dists
-distributionUrl=https\://services.gradle.org/distributions/gradle-9.5.0-bin.zip
+distributionUrl=https\://services.gradle.org/distributions/gradle-9.6.1-bin.zip
 networkTimeout=10000
 retries=0
 retryBackOffMs=500