Add precommit config and fix problems

[coveralls]

Pull Request Test Coverage Report for Build 7355892806

• 6 of 26 (23.08%) changed or added relevant lines in 9 files are covered.
• 2 unchanged lines in 2 files lost coverage.
• Overall coverage increased (+0.2%) to 38.584%

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Changes Missing Coverage	Covered Lines	Changed/Added Lines	%
cp2kdata/output.py	2	3	66.67%
cp2kdata/dpdata_plugin.py	0	2	0.0%
cp2kdata/plots/fep_plot.py	0	2	0.0%
cp2kdata/test_input.py	0	2	0.0%
cp2kdata/utils.py	0	4	0.0%
cp2kdata/plots/test_plot.py	0	9	0.0%
<!--	Total:	6	26	23.08%	-->

Files with Coverage Reduction	New Missed Lines	%
cp2kdata/dpdata_plugin.py	1	62.31%
cp2kdata/utils.py	1	54.17%
<!--	Total:	2		-->

Totals
Change from base Build 7330414483:	0.2%
Covered Lines:	752
Relevant Lines:	1949

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💛 - Coveralls