Use gradle-versions-plugin to check for dependency updates.

[johnjohndoe]

Description

• This allows to manually check for new versions of the project's dependencies from time to time.
• This plugin adds the dependencyUpdates Gradle task.
• Version 0.27.0 is used because it is the last version being compatible with the Gradle version used in this project.
• Plugin website: https://github.com/ben-manes/gradle-versions-plugin

Command + example output

$ ./gradlew dependencyUpdates

------------------------------------------------------------
: Project Dependency Updates (report to plain text file)
------------------------------------------------------------

The following dependencies have later milestone versions:
 - com.github.ben-manes:gradle-versions-plugin [0.27.0 -> 0.33.0]
     https://github.com/ben-manes/gradle-versions-plugin
 - net.opacapp:libopac [5.2.5 -> 6.2.7]
 - org.bouncycastle:bcprov-jdk16 [1.45 -> 1.46]
     http://www.bouncycastle.org/java.html
 - org.junit.jupiter:junit-jupiter-api [5.0.2 -> 5.7.0]
     https://junit.org/junit5/
 - org.springframework.boot:spring-boot-gradle-plugin [2.0.0.RELEASE -> 2.3.4.RELEASE]
     https://spring.io/projects/spring-boot
 - org.springframework.boot:spring-boot-starter-test [2.0.0.RELEASE -> 2.3.4.RELEASE]
     https://spring.io/projects/spring-boot
 - org.springframework.boot:spring-boot-starter-web [2.0.0.RELEASE -> 2.3.4.RELEASE]
     https://spring.io/projects/spring-boot

Gradle current updates:
 - Gradle: [4.6 -> 6.6.1]

Generated report file build/dependencyUpdates/report.txt

[johnjohndoe]

@k-nut, @annaira Do you think this will make a good addition to the project?