Bump external/bpf_conformance from b1b1c21 to 1ce2861

Bumps [external/bpf_conformance](https://github.com/Alan-Jowett/bpf_conformance) from `b1b1c21` to `1ce2861`.
- [Release notes](https://github.com/Alan-Jowett/bpf_conformance/releases)
- [Commits](Alan-Jowett/bpf_conformance@b1b1c21...1ce2861)

---
updated-dependencies:
- dependency-name: external/bpf_conformance
  dependency-type: direct:production
...

Signed-off-by: dependabot[bot] <[email protected]>