Upgrade dependencies

[nroulon]

Resolves #172

[nroulon]

Upgrade :

• gradle to 6.1.1. (Upgrade to 7 later)
• kotlin to 1.5.31
• kotlinx to 1.3.1
• mongo driver (on test) to 3.9.1
• Use mavenCentral over jcenter (jcenter is shutdown)

TODO :

• Remove mongo test plugin and user testcontainers.
• Upgrade gradle to version 7
• Fix test on CI (if testcontainers does not work)

[nroulon]

As I do not understand why the CI fail once but success with no change I make some modifications

1. add test-logger dependency that print if a test pass or not and the error : https://github.com/radarsh/gradle-test-logger-plugin#gradle-test-logger-plugin
2. The CI was using default console mode of gradle, I changed it to plain because in default the output was duplicated with just the percent increasing