Replace tap-gtester with one that relies on GLib 2.38+ TAP output
GLib 2.38 has been a hard dependency since gcr 3.13.91 (2014) so there is little point in trying to accommodate older versions.
This resolves build-time test failures when built with GLib 2.61+, where --tap is the default. The previous (Python) implementation of tap-gtester attempted to auto-detect whether the output was TAP or GTester, but detected GLib 2.61+ as GTester.
Signed-off-by: Simon McVittie smcv@debian.org
Fixes: #26 (closed)