Update pqreader.py

[jacrossley]

Changes made in previous commit (https://github.com/Photon-HDF5/phconvert/pull/58#issue-2315285880) which implemented code from this response (https://github.com/Photon-HDF5/phconvert/issues/56#issuecomment-2090728466) placed rtMultiHarpNT3 under the wrong record resulting in failure to convert these files.

I fix that here and change the nomenclature to what PQ are using now, covering a wider range of hardware.

• 'rtMultiHarpNT3' was added to wrong record type (produced error when trying to convert), deleted (ln 125).
• Changed 'rtMultiHarpNT3/2' to match new PQ , i.e., Generic (ln 78/79).
• Added 'rtGenericT3' to correct record type (ln121).

[harripd]

I'm also working on a larger overhaul of reading ptu files, as

• Overflow markers are left in the output and notebooks manually remove them
• There are 2 different types of overflows, only one of which is handled in the current version
• Similarly, other markers are potentially included, with no additional processing

Photon HDF5 doesn't have an official way of handling markers used for FLIM etc, I believe we may want to take this up with the photon HDF5 group soon, it would be good if raw data for FLIM images was transferable with photon HDF5, but for now they should be removed.