[Build] Add beta 2.1 dependency

This was missing due to a bad retargeting revert.

Signed-off-by: Elliot Morris <[email protected]>

pyproject.toml

@@ -5,7 +5,7 @@
 name = "openassetio-manager-bal"
 version = "1.0.0a14"
 requires-python = ">=3.7"
-dependencies = ["openassetio-mediacreation>=1.0.0a7"]
+dependencies = ["openassetio>=1.0.0b2.rev1", "openassetio-mediacreation>=1.0.0a7"]
 
 authors = [
   { name = "Contributors to the OpenAssetIO project", email = "[email protected]" }