refactor(tmpl): avoid unnecessary byte/string conversion

[Juneezee]

We can use (*regexp.Regexp).MatchString instead of (*regexp.Regexp).Match([]byte(...)) to avoid unnecessary []byte conversions and reduce allocations. A one-line change for free performance gain.

Benchmark:

func BenchmarkMatch(b *testing.B) {
	for i := 0; i < b.N; i++ {
		if match := envOnlyRe.Match([]byte("{{ .Env.FOO }}")); !match {
			b.Fail()
		}
	}
}

func BenchmarkMatchString(b *testing.B) {
	for i := 0; i < b.N; i++ {
		if match := envOnlyRe.MatchString("{{ .Env.FOO }}"); !match {
			b.Fail()
		}
	}
}

Result:

goos: linux
goarch: amd64
pkg: github.com/goreleaser/goreleaser/internal/tmpl cpu: AMD Ryzen 7 PRO 4750U with Radeon Graphics
BenchmarkMatch-16          	 4320873	       381.2 ns/op	      16 B/op	       1 allocs/op
BenchmarkMatchString-16    	 5973543	       203.9 ns/op	       0 B/op	       0 allocs/op
PASS
ok  	github.com/goreleaser/goreleaser/internal/tmpl	3.366s

[codecov]

Codecov Report

Merging #4356 (0da5c92) into main (c43a50c) will decrease coverage by 0.01%.
The diff coverage is 100.00%.

@@            Coverage Diff             @@
##             main    #4356      +/-   ##
==========================================
- Coverage   83.88%   83.88%   -0.01%     
==========================================
  Files         133      133              
  Lines       12703    12702       -1     
==========================================
- Hits        10656    10655       -1     
  Misses       1630     1630              
  Partials      417      417              

Files	Coverage Δ
internal/tmpl/tmpl.go	98.45% <100.00%> (-0.01%)	⬇️

[caarlos0]

awesome, thanks!