Update pydicom to 2, pynetdicom to 1.5

[Ed McDonagh]

Requirements, Dockerfile, upgrade instructions, pipeline tests

[Ed McDonagh]

Unfortunately pynetdicom is pinned to pydicom 1.4.2: https://github.com/pydicom/pynetdicom/issues/493

I’ve built Docker locally, and though it complains it appears to allow me the combination of pynetdicom 1.5.0 with pydicom 2.0.0.

[Ed McDonagh]

Installs pynetdicom 1.5 and pydicom 2.0 in docker container, but complains due to dependency requirement. Refs #836

→ <<cset c78d7cce630e>>

[Ed McDonagh]

Marked a couple of files to be updated/deleted. Added ref #836 to changes.

→ <<cset 64426e4875c4>>

[Ed McDonagh]

Merged in issue836updatepynetdicom (pull request #373)

FIxes #836

→ <<cset 819d29c7ca55>>