ChkTeX color output broken on Alpine Linux

[tueda]

ChkTeX v1.7.6 - Copyright 1995-96 Jens T. Berger Thielemann.
Compiled with POSIX extended regex support.
No errors printed; One warning printed; No user suppressed warnings; No line suppressed warnings.
See the manual for how to suppress some or all of these warnings/errors.
x1b[35mWarning 13 in test.tex line 3: Intersentence spacing (`\@') should perhaps be used.x1b[0m
This is a TEST.
              ^

The cause seems to be that a sed regex uses GNU extensions. Thus a workaround is to install GNU sed:

apk add sed