Remove unused variables causing compilation warnings

[GuillaumeLagrange]

fixes #11

[codspeed-hq]

CodSpeed Instrumentation Performance Report

Merging #14 will not alter performance

_{Comparing cod-1032-warnings-generated-when-building-workerd (d68b802) with main (308c879)}

Summary

✅ 42 untouched benchmarks

[codspeed-hq]

CodSpeed WallTime Performance Report

Merging #14 will degrade performances by 33.33%

_{Comparing cod-1032-warnings-generated-when-building-workerd (d68b802) with main (308c879)}

Summary

⚡ 4 improvements
❌ 4 regressions
✅ 34 untouched benchmarks

⚠️ Please fix the performance issues or acknowledge them on CodSpeed.

Benchmarks breakdown

	Benchmark	BASE	HEAD	Change
⚡	BarTest[MyFixture]	< 1 ns	< 1 ns	+20%
❌	DoubleTest[MyTemplatedFixture, double]	< 1 ns	< 1 ns	-16.67%
❌	IntTest[MyTemplatedFixture, int]	< 1 ns	< 1 ns	-33.33%
❌	TestA[MyTemplate1, int]	< 1 ns	< 1 ns	-20%
⚡	TestB[MyTemplate2, int, double]	< 1 ns	< 1 ns	+20%
❌	BM_Capture[int_string_test]	< 1 ns	< 1 ns	-16.67%
⚡	BM_Capture[int_test]	< 1 ns	< 1 ns	+20%
⚡	BM_Template1_Capture[two_type_test, int, double]	< 1 ns	< 1 ns	+20%

[not-matthias]

LGTM!