Fix various minor issues (#545)

* Add absolute URL to power tests

* Update to target Python 3.10

* Return user to current page when clicking 'mark reviewed'

* Add units to power test record detail and form

I'm a bad scientist (coz I'm an engineer)

* Allow a higher value in PSSC fields

* Default venue to event venue in EC/PT

* Fix population of initial venue values for EC/PT

* Add link to create power test from EC detail

* Do not set power plan field to required on RA

"This might be a problem if the risk assessment is being done by one person and the power plan by another."

* Default power MIC to MIC

* Implement some suggestions from the Doctor

* Prevent checking in to cancelled events and dry hires

Will close #539

* Exclude dry hires from H&S overview list

* Add "ex VAT" tooltips to asset purchase price and replacement cost

* Automagically clear and focus ID field when audit modal closes

Closes #533

* Delete unused things

* Allow two decimal places in cable length, show training item IDs in selectpicker

Will close #540

* Fix #524 500 Error when viewing qualification list for items nobody is qualified in

* Update README.md

* Add a guard against nulls in recent changes

Maybe fixes #537 I'm unable to replicate locally

* Turn down verbosity of CI tests, fix tests, potential speedup

* Squash migration

* Add encoding to open

* Update to v3 upload-artifact

Resolves a deprecation warning

versioning/versioning.py

@@ -160,7 +160,10 @@ class ModelComparison:
             # Build some dicts of what we have
             item_dict = {}  # build a list of items, key is the item_pk
             for version in old_item_versions:  # put all the old versions in a list
-                compare = ModelComparison(old=version._object_version.object, **comparisonParams)
+                old = version._object_version.object
+                if old is None:
+                    pass
+                compare = ModelComparison(old=old, **comparisonParams)
                 item_dict[version.object_id] = compare
 
             for version in new_item_versions:  # go through the new versions