migrations: Moved squashed migration

This should have been in the 'patchwork/migrations' directory, not
'migrations.

Signed-off-by: Stephen Finucane <stephen@that.guru>
Fixes: 9bb5caec ("migrations: Squash 0001 to 0040")

diff --git a/migrations/0001_squashed_0040_add_related_patches.py b/patchwork/migrations/0001_squashed_0040_add_related_patches.py
similarity index 100%
rename from migrations/0001_squashed_0040_add_related_patches.py
rename to patchwork/migrations/0001_squashed_0040_add_related_patches.py