Enhancement: Extract environment variable

[localheinz]

This PR

• extracts a COMPOSER_VERSION environment variable

[codecov]

Codecov Report

Merging #365 into master will not change coverage.
The diff coverage is n/a.

@@            Coverage Diff            @@
##             master     #365   +/-   ##
=========================================
  Coverage     87.43%   87.43%           
  Complexity       38       38           
=========================================
  Files             4        4           
  Lines           191      191           
=========================================
  Hits            167      167           
  Misses           24       24

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