Update RateCalculator.php

[habibhaidari1]

Using the interface makes you more flexible, so that you can change the rate service if necessary.

Description

A clear and concise description of what this pull request adds or changes.

Types of changes

• Bug fix (non-breaking change which fixes an issue)
• New feature (non-breaking change which adds functionality)
• Breaking change (fix or feature that would cause existing functionality to change)

Checklist

• I verified that my code applies to the guidelines (composer code-check)
• I updated the documentation (see here)
• I agree that this code is used in Kimai (see license)

[CLAassistant]

All committers have signed the CLA.

[habibhaidari1]

A bit of context:
The current rate calculator calculates the rate with second precision, but the items on the invoices are accurate to the hour with 2 decimal digits. This results in minimal rounding errors. So I made a little change in the Util class that forced me to override the whole service. I made these changes inside a bundle with the help of a compilerpass since I like to keep the core clean.

[kevinpapst]

Can you share the other changes in a separate PR?

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 87.78%. Comparing base (e042ef6) to head (b197d6b).

Additional details and impacted files

@@             Coverage Diff              @@
##               main    #4851      +/-   ##
============================================
+ Coverage     87.77%   87.78%   +0.01%     
  Complexity     8963     8963              
============================================
  Files           797      797              
  Lines         29414    29414              
============================================
+ Hits          25819    25822       +3     
+ Misses         3595     3592       -3     

Files	Coverage Δ
src/Timesheet/Calculator/RateCalculator.php	100.00% <100.00%> (ø)

... and 2 files with indirect coverage changes

[kevinpapst]

Thanks @habibhaidari1 👍