Format Depth decimals for Time and Cross section correlation plots

[fanisvl]

This is a minor fix to make the time and cross section correlation plots cleaner.

Before

After

[fanisvl]

You can replicate the issue with the test event.

./gisola.py -c ../test/config.yaml --event-xml ../test/benchmark/event.xml

[nikosT]

@fanisvl is it still there after configuration changes?

[fanisvl]

@nikosT Not sure what configuration changes you're referring to