perf: avoid using write! macro with single str

[DaniPopes]

A known issue with write! is that it's slower and generates more code than direct calls to write_str, unfortunately even in the simple case of "{str}". See rust-lang/rust#76490.

I've verified with Godbolt that it is still the case: https://godbolt.org/z/sq3M8xWfo

[coveralls]

Pull Request Test Coverage Report for Build 11629840392

Details

• 4 of 4 (100.0%) changed or added relevant lines in 3 files are covered.
• No unchanged relevant lines lost coverage.
• Overall coverage decreased (-0.06%) to 51.742%

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Totals
Change from base Build 11506573894:	-0.06%
Covered Lines:	1218
Relevant Lines:	2354

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💛 - Coveralls