Update dependency org.springframework.boot:spring-boot-starter-parent to v2.7.15

Author: renovate[bot]

pom.xml

@@ -11,7 +11,7 @@
     <parent>
         <groupId>org.springframework.boot</groupId>
         <artifactId>spring-boot-starter-parent</artifactId>
-        <version>2.7.14</version>
+        <version>2.7.15</version>
         <relativePath/>
     </parent>