bug: workaround go1.23 regression in goroutine profile

See https://go-review.googlesource.com/c/go/+/609815 for details.

Fixes #33

go.mod: upgrade pprof

Also fix a test that is sensitive to the way pprof stringifies profiles.
And while at it, fix the wrong ordering of got and want.

Fixes #27

README: Update for Go 1.19

Update pprof

Merge pull request #4 from felixge/gh-3

Default to 30s duration like net/http/pprof

Add shields