Reduce binary size by 75%

[Arnie97]

The patch removes regex from phantun's transitive dependencies, which was only used to support a rarely used env_logger feature to filter logs. (syslog-ng or egrep fits better if anyone needs log filters...)

I also cherry-picked #165 to fix its merge conflict against main branch.

Here are the final results (Tested with: Rust 1.96.0, target stable-x86_64-unknown-linux-gnu):

version	size	reduction
main branch	3488K	-0.0%
regex removed	2168K	-37.8%
compile flags applied	848K	-75.7%

[Arnie97]

This PR also solves #101 and #118 for free, because env_logger includes ISO 8601-formatted timestamps by default, unlike the dropped crate pretty_env_logger.