Unpin mysql-router version in db-router tests

[shayancanonical]

Bug Description

Due to the following bug in mysql-router reactive charm, we had to pin the mysql router channel to 8.0/latest here and here. This issue is a reminder to unpin the channel once the 8.0/latest channel is promoted to lastest/stable

To Reproduce

n/a

Environment

n/a

Relevant log output

n/a

Additional context

No response

[taurus-forever]

Just for the history, this is still topical.

The launchpad issue is resolved with the reference to commit cfe6b2e, which is in 8.0/stable but still not in latest/stable :-(

> juju info mysql-router
...
channels: |
  8.0/stable:        cfe6b2e  2022-08-23  (35)  15MB
  8.0/candidate:     ↑
  8.0/beta:          ↑
  8.0/edge:          5ee0683  2022-10-20  (47)  15MB
  latest/stable:     15       2022-02-09  (15)  13MB
  latest/candidate:  ↑
  latest/beta:       ↑
  latest/edge:       cd2738e  2022-10-20  (46)  15MB
  dpe/stable:        –
  dpe/candidate:     –
  dpe/beta:          –
  dpe/edge:          60       2022-11-25  (60)  29MB
  8.0.19/stable:     18cff04  2022-05-05  (26)  14MB
  8.0.19/candidate:  ↑
  8.0.19/beta:       ↑
  8.0.19/edge:       18cff04  2022-05-05  (26)  14MB