Tag has concurrent access problem

[diwufeiwen]

Please answer these questions before submitting a bug report.

What version of OpenCensus are you using?

go.opencensus.io v0.23.0

What version of Go are you using?

go version go1.18.2

What did you do?

If possible, provide a recipe for reproducing the error.

What did you see instead?

go.opencensus.io@v0.23.0/tag/map.go#L36

// Map is a map of tags. Use New to create a context containing
// a new Map.
type Map struct {
m map[Key]tagContent
}

No locking, not thread safe.

go func() {
ctx, _ = tag.New(ctx, tag.Upsert(***)
stats.Record(ctx, ...)
}

It will panic when there is a lot of concurrency