Enhancement: Allow creation of Header without File

[localheinz]

This pull request

• allows creation of Header without File

[codecov]

Codecov Report

Merging #534 (f1b966f) into main (4c72d0b) will increase coverage by 0.05%.
The diff coverage is 100.00%.

❗ Current head f1b966f differs from pull request most recent head 0152f09. Consider uploading reports for the commit 0152f09 to get more accurate results

@@             Coverage Diff              @@
##               main     #534      +/-   ##
============================================
+ Coverage     98.70%   98.76%   +0.05%     
- Complexity       58       60       +2     
============================================
  Files            14       14              
  Lines           155      162       +7     
============================================
+ Hits            153      160       +7     
  Misses            2        2              

Impacted Files	Coverage Δ
src/Header.php	100.00% <100.00%> (ø)

📣 We’re building smart automated test selection to slash your CI/CD build times. Learn more