Bump Terraform provider version to v4.64.0

[turkenf]

Description of your changes

Bump Terraform provider version to v4.64.0.

I have:

• Run make reviewable test to ensure this PR is ready for review.

How has this code been tested

Breaking CRD schema changes

Since Job failed, we did this check manually. We run make crddiff MODIFIED_CRD_LIST="$(git diff --name-only HEAD^ package/crds)" command and there are no Breaking CRD schema changes.

Native state schema version changes

❯ make schema-version-diff GITHUB_BASE_REF=85c8876c15b6abc73a17e372915c0dcb8536ee9d
14:29:20 [ .. ] Checking for native state schema version changes
Detected previous Terraform provider version: 4.56.0
Current Terraform provider version: 4.64.0
Reporting schema changes between "/Users/alper/data/workspaces/github.com/ulucinar/upbound/provider-gcp/.work/schema.json.4.56.0" as base version and "config/schema.json" as bumped version
google_certificate_manager_certificate:0-1
14:29:20 [ OK ] Checking for native state schema version changes

• google_certificate_manager_certificate, Manually

NAME                                                    READY   SYNCED   EXTERNAL-NAME   AGE
certificate.certificatemanager.gcp.upbound.io/default   True    True     default         4m35s

NAME                                                         READY   SYNCED   EXTERNAL-NAME   AGE
dnsauthorization.certificatemanager.gcp.upbound.io/default   True    True     default         4m35s

[sergenyalcin]

Thanks @turkenf LGTM!