Upgrade spring-boot-maven-plugin to 2.7.6

provider/notification-reference/pom.xml

@@ -18,6 +18,7 @@
     <java.version>8</java.version>
     <maven.compiler.target>${java.version}</maven.compiler.target>
     <maven.compiler.source>${java.version}</maven.compiler.source>
+    <spring-boot-maven-plugin.version>2.7.6</spring-boot-maven-plugin.version>
   </properties>
 
   <dependencies>
@@ -89,6 +90,7 @@
       <plugin>
         <groupId>org.springframework.boot</groupId>
         <artifactId>spring-boot-maven-plugin</artifactId>
+        <version>${spring-boot-maven-plugin.version}</version>
         <configuration>
           <profiles>
             <profile>
@@ -149,4 +151,4 @@
       </plugin>
     </plugins>
   </build>
-</project>
\ No newline at end of file
+</project>