Collecting fairseq2
  Downloading fairseq2-0.2.1-py3-none-any.whl.metadata (1.2 kB)
INFO: pip is looking at multiple versions of fairseq2 to determine which version is compatible with other requirements. This could take a while.
  Downloading fairseq2-0.2.0-py3-none-any.whl.metadata (1.2 kB)
  Downloading fairseq2-0.1.1-py3-none-any.whl.metadata (1.2 kB)
  Downloading fairseq2-0.1.0-py3-none-any.whl.metadata (1.2 kB)
ERROR: Cannot install fairseq2==0.1.0, fairseq2==0.1.1, fairseq2==0.2.0 and fairseq2==0.2.1 because these package versions have conflicting dependencies.

The conflict is caused by:
    fairseq2 0.2.1 depends on fairseq2n==0.2.1
    fairseq2 0.2.0 depends on fairseq2n==0.2.0
    fairseq2 0.1.1 depends on fairseq2n==0.1.1
    fairseq2 0.1.0 depends on fairseq2n==0.1.0

To fix this you could try to:
1. loosen the range of package versions you've specified
2. remove package versions to allow pip attempt to solve the dependency conflict

ERROR: ResolutionImpossible: for help visit https://pip.pypa.io/en/latest/topics/dependency-resolution/#dealing-with-dependency-conflicts