add spring-boot-test dependency to fix packaging failure

[mydiemho]

Running mvn clean package -DskipTests resulted in the following error

[INFO] auth-service 1.0-SNAPSHOT .......................... SUCCESS [  2.042 s]
[INFO] account-service 1.0-SNAPSHOT ....................... FAILURE [  1.687 s]
[INFO] statistics-service 1.0-SNAPSHOT .................... SKIPPED
[INFO] notification-service 1.0.0-SNAPSHOT ................ SKIPPED
[INFO] turbine-stream-service 0.0.1-SNAPSHOT .............. SKIPPED

...

[ERROR] Failed to execute goal org.apache.maven.plugins:maven-compiler-plugin:3.8.1:testCompile (default-testCompile) on project account-service: Compilation failure: Compilation failure: 
[ERROR] /Users/myho/dev/work/learning/spring/piggymetrics/account-service/src/test/java/com/piggymetrics/account

[BhargaviAnnadevara]

@xscript Could you please review and approve these changes? More details here: MicrosoftDocs/azure-docs/issues/62778