when deleting run , pool and library_preparations are also deleted

[luissian]

Description of the bug

When a run is created through the samples collection data, and when continuing with the library preparation are assigned to a pool and this pool to a run, then when using django admin to delete the run, pool and those library preparation are also deleted

Command used and terminal output

Using django admin , delete a run.

Relevant files

No response

System information

iSkyLIMs version 2.3.0.

A possible solution is class LibraryPool(models.Model)
`

register_user = models.ForeignKey(User, on_delete=models.CASCADE)
pool_state = models.ForeignKey(PoolStates, on_delete=models.CASCADE)
run_process_id = models.ForeignKey(
    RunProcess, on_delete=models.CASCADE, null=True, blank=True
)

`
Change the relation of run_process_id from ForeignKey to ManyToMany relation.

[luissian]

To fix this issue is required the following changes:
1. Create a new field run_process with a many to many relation to RunProcess
2. Run the script during upgrade to collect all existing information on the run_process_id field.
Which collects data from old field and set in the new one.
3. Modify the code to change the old field to the new one.

[luissian]

implemented on PR #262