azkv: update Azure SDK to v0.6.0

[hiddeco]

This depends on #1091 being merged into develop first, as I took the go.mod file state from there as a base.

Other than that, this PR does nothing more than dealing with the method (signature) and client construction changes from the v0.6.0 release of the azkeys module. This should be the last major change in their SDK.

I manually ran the integration test suite which passes without any issues:

$ go test -json -tags integration ./...
=== RUN   TestMasterKey_Encrypt
--- PASS: TestMasterKey_Encrypt (1.66s)
=== RUN   TestMasterKey_Decrypt
--- PASS: TestMasterKey_Decrypt (1.00s)
=== RUN   TestMasterKey_EncryptDecrypt_RoundTrip
--- PASS: TestMasterKey_EncryptDecrypt_RoundTrip (0.48s)
...
PASS
ok  	go.mozilla.org/sops/v3/azkv	5.069s

Process finished with the exit code 0

[hiddeco]

Tested this with an EncryptedData value created with current develop, and it decrypts successfully with this branch.