Bump peewee-migrate from 1.14.3 to 1.15.0 in /backend

Bumps [peewee-migrate](https://github.com/klen/peewee_migrate) from 1.14.3 to 1.15.0.
- [Changelog](https://github.com/klen/peewee_migrate/blob/develop/Changelog)
- [Commits](https://github.com/klen/peewee_migrate/commits/1.15.0)

---
updated-dependencies:
- dependency-name: peewee-migrate
  dependency-version: 1.15.0
  dependency-type: direct:production
  update-type: version-update:semver-minor
...

Signed-off-by: dependabot[bot] <support@github.com>

backend/requirements-min.txt

@@ -31,7 +31,7 @@ aiosqlite==0.21.0
 psycopg[binary]==3.2.9
 alembic==1.18.4
 peewee==3.19.0
-peewee-migrate==1.14.3
+peewee-migrate==1.15.0
 
 pycrdt==0.12.47
 redis

backend/requirements.txt

@@ -29,7 +29,7 @@ aiosqlite==0.21.0
 psycopg[binary]==3.2.9
 alembic==1.18.4
 peewee==3.19.0
-peewee-migrate==1.14.3
+peewee-migrate==1.15.0
 
 pycrdt==0.12.47
 redis==7.4.0