tests: use grep -F instead of obsolescent fgrep
Testing on Fedora 38 failed with:
fgrep: warning: fgrep is obsolescent; using grep -F
The warning comes from
https://git.savannah.gnu.org/cgit/grep.git/commit/?id=
a9515624709865d480e3142fd959bccd1c9372d1
. For further anecdotal evidence of the change, see
https://www.phoronix.com/news/GNU-Grep-3.8-Stop-egrep-fgrep .
grep -F is POSIX, but there is a risk that it doesn't work the same on all
platforms - especially older Unix versions. It should however always be
possible to put a GNU grep in $PATH before running the tests.
# See http://EditorConfig.org for the specification
root = true
[*.py]
indent_size = 4
indent_style = space
trim_trailing_whitespace = true
end_of_line = lf
[*.{c,h}]
indent_size = 8
indent_style = tab
trim_trailing_whitespace = true
end_of_line = lf
[*.t]
indent_size = 2
indent_style = space
trim_trailing_whitespace = false
end_of_line = lf