Bumped version of Spring Boot in order to fix same issue as https://github.com/Haulmont/jmix-security/issues/90

pom.xml

@@ -21,6 +21,7 @@
 
     <properties>
         <java.version>8</java.version>
+        <spring_boot_version>2.5.6</spring_boot_version>
     </properties>
 
     <prerequisites>
@@ -69,6 +70,7 @@
         <dependency>
             <groupId>com.sun.mail</groupId>
             <artifactId>javax.mail</artifactId>
+            <version>1.6.2</version>
             <exclusions>
                 <exclusion>
                     <groupId>javax.activation</groupId>