Bump quarkus.platform.version from 3.7.4 to 3.8.1 in /backend (#26)

Bumps `quarkus.platform.version` from 3.7.4 to 3.8.1.

Updates `io.quarkus.platform:quarkus-bom` from 3.7.4 to 3.8.1
- [Commits](quarkusio/quarkus-platform@3.7.4...3.8.1)

Updates `io.quarkus.platform:quarkus-maven-plugin` from 3.7.4 to 3.8.1
- [Commits](quarkusio/quarkus-platform@3.7.4...3.8.1)

---
updated-dependencies:
- dependency-name: io.quarkus.platform:quarkus-bom
  dependency-type: direct:production
  update-type: version-update:semver-minor
- dependency-name: io.quarkus.platform:quarkus-maven-plugin
  dependency-type: direct:production
  update-type: version-update:semver-minor
...

Signed-off-by: dependabot[bot] <support@github.com>
Co-authored-by: dependabot[bot] <49699333+dependabot[bot]@users.noreply.github.com>

backend/pom.xml

@@ -13,7 +13,7 @@
         <project.reporting.outputEncoding>UTF-8</project.reporting.outputEncoding>
         <quarkus.platform.artifact-id>quarkus-bom</quarkus.platform.artifact-id>
         <quarkus.platform.group-id>io.quarkus.platform</quarkus.platform.group-id>
-        <quarkus.platform.version>3.7.4</quarkus.platform.version>
+        <quarkus.platform.version>3.8.1</quarkus.platform.version>
         <skipITs>true</skipITs>
         <surefire-plugin.version>3.2.5</surefire-plugin.version>
     </properties>