Bump flatten-maven-plugin from 1.4.1 to 1.5.0 #613

All 399 tests pass in 1m 32s

399 tests ±0 399 ✔️ ±0 1m 32s ⏱️ -26s
  85 suites ±0     0 💤 ±0
  85 files ±0     0 ❌ ±0

Results for commit f6f3847. ± Comparison against earlier commit a0cc38d.