Update SRF_Calendar.php

[krabina]

first day of week issue
#138

[krabina]

@paladox @gesinn-it-gea any idea why this is failing?

[codecov]

Codecov Report

Attention: Patch coverage is 0% with 1 line in your changes missing coverage. Please review.

Project coverage is 45.55%. Comparing base (48c9a17) to head (6affed1).
Report is 1 commits behind head on master.

Files with missing lines	Patch %	Lines
formats/calendar/SRF_Calendar.php	0.00%	1 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff            @@
##             master     #929   +/-   ##
=========================================
  Coverage     45.55%   45.55%           
  Complexity     2318     2318           
=========================================
  Files            80       80           
  Lines          9044     9044           
=========================================
  Hits           4120     4120           
  Misses         4924     4924           

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[paladox]

It's just codecov failing because a line you touched isn't covered by tests.

[JeroenDeDauw]

It's just codecov failing because a line you touched isn't covered by tests.

That are some bad codecov settings then