Update dependency org.springframework.boot:spring-boot-starter-parent to v2.6.6

Author: renovate-bot

pom.xml

@@ -5,7 +5,7 @@
     <parent>
         <groupId>org.springframework.boot</groupId>
         <artifactId>spring-boot-starter-parent</artifactId>
-        <version>2.4.5</version>
+        <version>2.6.6</version>
         <relativePath/> <!-- lookup parent from repository -->
     </parent>
     <groupId>de.filefighter</groupId>