Bump org.springframework.boot:spring-boot-starter-jdbc in /backend

Bumps [org.springframework.boot:spring-boot-starter-jdbc](https://github.com/spring-projects/spring-boot) from 3.5.3 to 3.5.7.
- [Release notes](https://github.com/spring-projects/spring-boot/releases)
- [Commits](spring-projects/spring-boot@v3.5.3...v3.5.7)

---
updated-dependencies:
- dependency-name: org.springframework.boot:spring-boot-starter-jdbc
  dependency-version: 3.5.7
  dependency-type: direct:production
  update-type: version-update:semver-patch
...

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

Author: dependabot[bot]

backend/pom.xml

@@ -53,7 +53,7 @@ SPDX-License-Identifier: MIT
         <dependency>
             <groupId>org.springframework.boot</groupId>
             <artifactId>spring-boot-starter-jdbc</artifactId>
-            <version>3.5.3</version>
+            <version>3.5.7</version>
         </dependency>
         <dependency>
             <groupId>com.mysql</groupId>