base: Bump nrf-regtool to 6.0.0

New fields for configuring the tracing subsystem were added here:
zephyrproject-rtos/zephyr#78831
nrf-regtool 6.0.0 supports those latest changes.

Signed-off-by: Karsten Koenig <karsten.koenig@nordicsemi.no>

Dockerfile.base

@@ -114,7 +114,7 @@ RUN python3 -m pip install -U --no-cache-dir pip && \
  -r https://raw.githubusercontent.com/zephyrproject-rtos/mcuboot/main/scripts/requirements.txt \
  GitPython imgtool junitparser junit2html numpy protobuf PyGithub \
  pylint sh statistics west \
- nrf-regtool>=5.3.0
+ nrf-regtool>=6.0.0
 # Run pip check on x86 only for now, it fails on arm.
 RUN if [ "${HOSTTYPE}" = "x86_64" ]; then \
  pip3 check \