Bump src/3dparty/JNet from 781a50b to a8536f1

Bumps [src/3dparty/JNet](https://github.com/masesgroup/JNet) from `781a50b` to `a8536f1`.
- [Release notes](https://github.com/masesgroup/JNet/releases)
- [Commits](masesgroup/JNet@781a50b...a8536f1)

---
updated-dependencies:
- dependency-name: src/3dparty/JNet
  dependency-type: direct:production
...

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