Migrate major version v2

[tomassatka]

Description of your changes

Since provider-vault is already beyond v2.0.0 it has to follow versioning principles for golang: https://go.dev/blog/v2-go-modules

Otherwise it causes issue when trying to use a go.mod dependency

When i first try to fetch it as dependency i get:

tomas@Tomass-MacBook-Pro svcs % go mod tidy
go: errors parsing go.mod:
go.mod:9:2: require github.com/upbound/provider-vault: version "v2.0.1" invalid: should be v0 or v1, not v2

That is confirmed by listing it:

tomas@Tomass-MacBook-Pro svcs % go list -m -versions github.com/upbound/provider-vault

github.com/upbound/provider-vault v0.1.0 v0.2.0 v0.3.0 v0.4.0 v1.0.0

I have:

• Read and followed Crossplane's contribution process.
• Run make reviewable test to ensure this PR is ready for review.

How has this code been tested

Executed all major make commands successfuly

[Upbound-CLA]

All committers have signed the CLA.