trc env_filter compatibility with tracing

[maasteh]

trc initializes tracing env_filter using LogSpecification::to_string https://github.com/emabee/flexi_logger/blob/main/src/trc.rs#L232
this adds spaces around = (for visibility I assume) https://github.com/emabee/flexi_logger/blob/main/src/log_specification.rs#L455

This is not compatible with tracing and evn_filters get incorrectly parsed, and ultimately ignored "ignoring crate = level: invalid filter directive".

removing the spaces seem to fix the issue. happy to put up a PR if it sounds reasonable.

[emabee]

An even better solution could be done on TRC side - they should be able to ignore the spaces!

If we change flexi_logger to not print out spaces, we reduce the readability of the LogSpecification. We should at least compensate for this by adding an explicit display function that still prints with spaces.

[maasteh]

#200
please let me know what your thoughts

[emabee]

Thanks for the good analysis and the PR!

[emabee]

This is now contained in version 0.31.6

[maasteh]

Thank you.