Add `retry` field to `ExperimentSpec` #1043

Job	Run time
Pydantic V1	18s
Docker	18s
Compatibility	25s
ubuntu-latest - python 3.8 - Lint	18s
ubuntu-latest - python 3.8 - Type check	20s
ubuntu-latest - python 3.8 - Unit tests	58s
ubuntu-latest - python 3.8 - Doc tests	4m 27s
ubuntu-latest - python 3.8 - Doc tests (B)	1m 13s
ubuntu-latest - python 3.8 - Images	1m 12s
ubuntu-latest - python 3.8 - Jobs	19s
ubuntu-latest - python 3.8 - Experiments	4m 27s
ubuntu-latest - python 3.8 - Datasets	54s
ubuntu-latest - python 3.8 - Sweep example	4m 25s
ubuntu-latest - python 3.8 - Build	22s
ubuntu-latest - python 3.8 - Style	18s
ubuntu-latest - python 3.8 - Docs	27s
Release	1s
	20m 42s

Provide feedback