Poseidon 2.7.0 and fstats-block-output

• This release updates the underlying Poseidon library, which makes this version now compatible with newest Poseidon packages of version 2.7.0.
• We also added a new feature to xerxes fstats to output statistics per Jackknife-block.
• The output was also prettified using our central log-functionality.
• The GHC compiler which this package depends upon has also been updated to a much newer release than the version before. In particular, this new compiler runs on the newest Mac M2 Macbook-Pros (which the previous ones did not)