We should use `(*regexp.Regexp).MatchString` instead of
`(*regexp.Regexp).Match([]byte(...))` when matching string to avoid
unnecessary `[]byte` conversions and reduce allocations.

Example benchmark:

func BenchmarkMatch(b *testing.B) {
	for i := 0; i < b.N; i++ {
		if match := pseudoSemverPattern.Match([]byte("1.0.0-beta-prerelease")); !match {
			b.Fail()
		}
	}
}

func BenchmarkMatchString(b *testing.B) {
	for i := 0; i < b.N; i++ {
		if match := pseudoSemverPattern.MatchString("1.0.0-beta-prerelease"); !match {
			b.Fail()
		}
	}
}

goos: linux
goarch: amd64
pkg: github.com/anchore/grype/grype/version
cpu: AMD Ryzen 7 PRO 4750U with Radeon Graphics
BenchmarkMatch-16          	 1378789	       889.7 ns/op	      24 B/op	       1 allocs/op
BenchmarkMatchString-16    	 2287442	       482.2 ns/op	       0 B/op	       0 allocs/op
PASS
ok  	github.com/anchore/grype/grype/version	3.632s

Signed-off-by: Eng Zer Jun <engzerjun@gmail.com>