Tagging a new release

Notable changes:

- reworked sysrepo pushed-ops data
- a Y2038-safe time_t build
- improvements for BIDI amps (e.g., AGC)
- better inventory support, with more SNs and optical calibration
- a more robust PMBus, with support for DC power supplies
- improved health alarms
- more robust communication with optical modules (including a
  preemptible kernel for improved latency)
- FW flashing improvements
- many other bugfixes and updates

Many new features, including:

- HW inventory (power supplies and EEPROMs on PCBs)
- YANG stack performance improvements and bugfixes
- bugfixes for flashing form USB
- docs updates

A new release, a.k.a. "it's been ages" since we tagged anything

ROADM software for the demo at the TIP Summit in Amsterdam

This powered the TIP Summit demo.

The first tag ever, yay.

This should be enough to run on a production run of PCBs.