fix: pom.xml to reduce vulnerabilities (#155)

The following vulnerabilities are fixed with an upgrade:
- https://snyk.io/vuln/SNYK-JAVA-ORGSPRINGFRAMEWORK-2436751
- https://snyk.io/vuln/SNYK-JAVA-ORGSPRINGFRAMEWORK-2689634

Author: snyk-bot

pom.xml

@@ -42,7 +42,7 @@
         <dependency>
             <groupId>org.springframework.boot</groupId>
             <artifactId>spring-boot</artifactId>
-            <version>2.4.5</version>
+            <version>2.5.13</version>
         </dependency>
 
         <dependency>