fix: `Span.trim_remainder` gave incorrect result if `after` was incom… #480

Job	Run time
License / vulnerability audit (advisories)	22s
Clippy	22s
Enforce Rust code format	16s
Test performance on benchmarks	32s
License / vulnerability audit (bans licenses sources)	16s
Preflight docs.rs build	15s
Preflight crate publish (ubuntu-latest, stable)	19s
Unit tests with minimum versions of direct dependencies (windows-latest)	43s
Check for unused dependencies	24s
Unit tests (windows-latest, stable)	2m 7s
Unit tests with minimum versions of direct dependencies (macos-latest)	22s
Unit tests with minimum versions of direct dependencies (ubuntu-latest)	21s
Unit tests (windows-latest, 1.74.0)	53s
Unit tests (macos-latest, stable)	27s
Unit tests (macos-latest, 1.74.0)	33s
Unit tests (ubuntu-latest, stable)	30s
Unit tests (ubuntu-latest, 1.74.0)	26s
	9m 8s

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