build(deps): bump spring.version from 5.3.23 to 6.0.0

Bumps `spring.version` from 5.3.23 to 6.0.0.

Updates `spring-context` from 5.3.23 to 6.0.0
- [Release notes](https://github.com/spring-projects/spring-framework/releases)
- [Commits](spring-projects/spring-framework@v5.3.23...v6.0.0)

Updates `spring-webmvc` from 5.3.23 to 6.0.0
- [Release notes](https://github.com/spring-projects/spring-framework/releases)
- [Commits](spring-projects/spring-framework@v5.3.23...v6.0.0)

Updates `spring-test` from 5.3.23 to 6.0.0
- [Release notes](https://github.com/spring-projects/spring-framework/releases)
- [Commits](spring-projects/spring-framework@v5.3.23...v6.0.0)

---
updated-dependencies:
- dependency-name: org.springframework:spring-context
  dependency-type: direct:production
  update-type: version-update:semver-major
- dependency-name: org.springframework:spring-webmvc
  dependency-type: direct:production
  update-type: version-update:semver-major
- dependency-name: org.springframework:spring-test
  dependency-type: direct:production
  update-type: version-update:semver-major
...

Signed-off-by: dependabot[bot] <support@github.com>

Author: dependabot[bot]

contrib/pom.xml

@@ -64,7 +64,7 @@
         <slf4j.version>1.7.32</slf4j.version>
         <gson.version>2.10</gson.version> <!-- Same version as grpc-proto -->
         <mustache-java.version>0.9.4</mustache-java.version>
-        <spring.version>5.3.23</spring.version>
+        <spring.version>6.0.0</spring.version>
 
         <!-- Test Dependency Versions -->
         <junit.version>4.13.2</junit.version>

demos/grpc-java-contrib-demo/time-service-demo/pom.xml

@@ -51,7 +51,7 @@
         <dependency>
             <groupId>org.springframework</groupId>
             <artifactId>spring-context</artifactId>
-            <version>5.3.23</version>
+            <version>6.0.0</version>
         </dependency>
         <dependency>
             <groupId>org.slf4j</groupId>

demos/pom.xml

@@ -64,7 +64,7 @@
         <slf4j.version>1.7.21</slf4j.version>
         <gson.version>2.10</gson.version> <!-- Same version as grpc-proto -->
         <mustache-java.version>0.9.4</mustache-java.version>
-        <spring.version>5.3.23</spring.version>
+        <spring.version>6.0.0</spring.version>
 
         <!-- Test Dependency Versions -->
         <junit.version>4.12</junit.version>