Removing unnecessary xdg-open

[jawira]

The default use of xdg-open forces installation of the xdg-utils package, since there's is no desktop environment in CI, it has no sense to use xdg-open.

In this PR I replace xdg-open with a symlink of /usr/bin/true (which always returns 0), this should speed up a little bit the pipelines since xdg-utils is not installed anymore.

Well, at the end "xdg-open" is not required in "static_code_analysis" step.

Aditionally, I had already set a "fake xdg-open" some lines below in the same file:

phing/.github/workflows/build.yml

Lines 98 to 101 in 7d28dac

	env:
	# Required by xdg-open (OpenTaskTest.php)
	# 'true' command will behave as a fake browser, always returning 0.
	BROWSER: /usr/bin/true

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 53.31%. Comparing base (7d28dac) to head (bea0138).
⚠️ Report is 1 commits behind head on main.

Additional details and impacted files

@@            Coverage Diff            @@
##               main    #1972   +/-   ##
=========================================
  Coverage     53.31%   53.31%           
  Complexity     9806     9806           
=========================================
  Files           495      495           
  Lines         24139    24139           
=========================================
  Hits          12870    12870           
  Misses        11269    11269           

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