fix(deps): Update module cloud.google.com/go/billing to v1.26.0

[renovate]

This PR contains the following updates:

Package	Change	Age	Confidence
cloud.google.com/go/billing	v1.20.1 → v1.26.0

---

Configuration

📅 Schedule: (UTC)

• Branch creation
  • At any time (no schedule defined)
• Automerge
  • At any time (no schedule defined)

🚦 Automerge: Disabled by config. Please merge this manually once you are satisfied.

♻ Rebasing: Whenever PR becomes conflicted, or you tick the rebase/retry checkbox.

🔕 Ignore: Close this PR and you won't be reminded about this update again.

---

• If you want to rebase/retry this PR, check this box

---

This PR was generated by Mend Renovate. View the repository job log.

[renovate]

ℹ️ Artifact update notice

File name: helpers/foundation-deployer/go.mod

In order to perform the update(s) described in the table above, Renovate ran the go get command, which resulted in the following additional change(s):

• 16 additional dependencies were updated

Details:

Package	Change
cloud.google.com/go/iam	v1.5.0 -> v1.7.0
cloud.google.com/go/resourcemanager	v1.10.6 -> v1.10.7
google.golang.org/api	v0.229.0 -> v0.274.0
cloud.google.com/go	v0.120.0 -> v0.123.0
cloud.google.com/go/longrunning	v0.6.6 -> v0.8.0
go.opentelemetry.io/contrib/instrumentation/google.golang.org/grpc/otelgrpc	v0.60.0 -> v0.61.0
google.golang.org/genproto	v0.0.0-20250303144028-a0af3efb3deb -> v0.0.0-20260319201613-d00831a3d3e7
google.golang.org/genproto/googleapis/api	v0.0.0-20251202230838-ff82c1b0f217 -> v0.0.0-20260401024825-9d38bb4040a9
cloud.google.com/go/auth	v0.16.0 -> v0.18.2
github.com/googleapis/enterprise-certificate-proxy	v0.3.6 -> v0.3.14
github.com/googleapis/gax-go/v2	v2.14.1 -> v2.21.0
go.opentelemetry.io/contrib/instrumentation/net/http/otelhttp	v0.60.0 -> v0.61.0
go.opentelemetry.io/otel	v1.39.0 -> v1.42.0
go.opentelemetry.io/otel/metric	v1.39.0 -> v1.42.0
go.opentelemetry.io/otel/trace	v1.39.0 -> v1.42.0
google.golang.org/grpc	v1.79.3 -> v1.80.0

[dpebot]

/gcbrun