chore: update to junit v6

[derklaro]

Motivation

JUnit v6 was released and we should update to it.

Modification

Update to junit v6.

Result

We're using the latest junit version.

[derklaro]

only open to track junit v6 milestones & the pmigration progress.

[github-actions]

Test Results

 56 files  ±0   56 suites  ±0   2m 23s ⏱️ -33s
566 tests ±0  566 ✅ ±0  0 💤 ±0  0 ❌ ±0 
931 runs  ±0  931 ✅ ±0  0 💤 ±0  0 ❌ ±0 

Results for commit 9c83505. ± Comparison against base commit ce44537.

This pull request removes 37 and adds 37 tests. Note that renamed tests count towards both.

eu.cloudnetservice.driver.impl.document.DocumentSerialisationTest ‑ [4] {"b":1,"s":2,"i":3,"l":4,"f":5.0,"d":6.0,"c":"/","string":"Hello, World!","bol":true,"cloud":["Ben?","Yes","No","HoHoHoHo"],"world":{"this":"is","insane":"!","hello":"world"}}, PRETTY
eu.cloudnetservice.driver.impl.document.gson.JavaTimeSerializerTest ‑ [14] 2025-07-03
eu.cloudnetservice.driver.impl.document.gson.JavaTimeSerializerTest ‑ [23] 07:17:26.178870846
eu.cloudnetservice.driver.impl.document.gson.JavaTimeSerializerTest ‑ [28] 07:17:26.178995468Z
eu.cloudnetservice.driver.impl.document.gson.JavaTimeSerializerTest ‑ [29] 07:17:26.179015926Z
eu.cloudnetservice.driver.impl.document.gson.JavaTimeSerializerTest ‑ [30] 07:17:26.179037616+05:00
eu.cloudnetservice.driver.impl.document.gson.JavaTimeSerializerTest ‑ [31] 07:17:26.179056110-03:00
eu.cloudnetservice.driver.impl.document.gson.JavaTimeSerializerTest ‑ [34] 2025-07-03T07:17:26.179176213
eu.cloudnetservice.driver.impl.document.gson.JavaTimeSerializerTest ‑ [39] 2025-07-03T07:17:26.179300935Z
eu.cloudnetservice.driver.impl.document.gson.JavaTimeSerializerTest ‑ [4] 2025-07-03T07:17:26.163922227Z
…

eu.cloudnetservice.driver.impl.document.DocumentSerialisationTest ‑ [4] {"b":1,"s":2,"i":3,"l":4,"f":5.0,"d":6.0,"c":"/","string":"Hello, World!","bol":true,"cloud":["Ben?","Yes","No","HoHoHoHo"],"world":{"this":"is","hello":"world","insane":"!"}}, PRETTY
eu.cloudnetservice.driver.impl.document.gson.JavaTimeSerializerTest ‑ [14] 2025-07-04
eu.cloudnetservice.driver.impl.document.gson.JavaTimeSerializerTest ‑ [23] 21:36:04.723048842
eu.cloudnetservice.driver.impl.document.gson.JavaTimeSerializerTest ‑ [28] 21:36:04.723147176Z
eu.cloudnetservice.driver.impl.document.gson.JavaTimeSerializerTest ‑ [29] 21:36:04.723168946Z
eu.cloudnetservice.driver.impl.document.gson.JavaTimeSerializerTest ‑ [30] 21:36:04.723192210+05:00
eu.cloudnetservice.driver.impl.document.gson.JavaTimeSerializerTest ‑ [31] 21:36:04.723210283-03:00
eu.cloudnetservice.driver.impl.document.gson.JavaTimeSerializerTest ‑ [34] 2025-07-04T21:36:04.723352829
eu.cloudnetservice.driver.impl.document.gson.JavaTimeSerializerTest ‑ [39] 2025-07-04T21:36:04.723502539Z
eu.cloudnetservice.driver.impl.document.gson.JavaTimeSerializerTest ‑ [4] 2025-07-04T21:36:04.710564184Z
…