Changes for v3

[ericchiang]

Since we need to modify the import path to make a go.mod work (#230), it might be a good chance to fix some APIs and call it v3.

Some changes that seem uncontroversial:

• Change import to github.com/coreos/go-oidc/v3/oidc
• Remove import of github.com/pquerna/cachecontrol (Internalize more dependencies #127)
• Separate NewProvider context and Verifier context (updateKeys for remoteKeySet uses wrong context #214)

Changes that are more intrusive:

• Don't use context keys to configure http.Clients? This pattern is popular in Google packages, but is generally discouraged (database/sql: don't encumber Context with options golang/go#18284). Would require a lot of API changes.
• Remove golang.org/x/oauth2 import? If you're just verifying ID Tokens, you generally don't need it. Would require changing the following signatures:

func Nonce(nonce string) oauth2.AuthCodeOption
func (p *Provider) Endpoint() oauth2.Endpoint
func (p *Provider) UserInfo(ctx context.Context, tokenSource oauth2.TokenSource) (*UserInfo, error)

[ericchiang]

Am going to move forward with this so we can add a go.mod file. I think I'll forgo the context and oauth2 import changes.

[ericchiang]

Hmm, some issues with the v3 path. Investigating

go get github.com/coreos/go-oidc/oidc@v3.0.0-alpha.1: github.com/coreos/go-oidc@v3.0.0-alpha.1: invalid version: module contains a go.mod file, so major version must be compatible: should be v0 or v1, not v3

Edit: figured it out

go get github.com/coreos/go-oidc/v3/oidc@v3.0.0-alpha.1

[ericchiang]

Okay I think we're at the point we can tag v3. Going to send a README update then call it done.

[ericchiang]

README PR sent (#232). Once that's in, I'll tag v3.0.0 and change the default branch to v3.

[ericchiang]

Tagged https://github.com/coreos/go-oidc/releases/tag/v3.0.0