Update dependency @bufbuild/buf to v1.26.1

[renovate]

This PR contains the following updates:

Package	Change	Age	Adoption	Passing	Confidence
@bufbuild/buf	1.25.1 -> 1.26.1

---

Release Notes

bufbuild/buf (@​bufbuild/buf)

v1.26.1

Compare Source

• Fix issue where buf build -o did not properly output files with the .txtpb
  extension in Protobuf text format.

v1.26.0

Compare Source

• Add support for the --http2-prior-knowledge flag when running buf curl
  against secure "https" URLs. This can be used with gRPC servers, that only
  support HTTP/2, when used with a network (layer 4) load balancer, that does
  not support protocol negotiation in TLS handshake.

---

Configuration

📅 Schedule: Branch creation - "before 10am on friday" (UTC), Automerge - At any time (no schedule defined).

🚦 Automerge: Enabled.

♻ 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 has been generated by Mend Renovate. View repository job log here.