Add Julia test workflow

[etpinard]

As discussed in #175 (comment), I think it would be easier to run the Julia ] test for different Julia versions inside a Github workflow instead of inside the plotly/julia:ci docker container.

Running Julia tests inside Github workflows is fairly easy now thanks to the julia-actions organisation. This should make it much easier to maintain the list of tested Julia versions for Dash.jl. It's much easier to patch a yaml file than updating a docker image, right? 😛

I'm thinking we could also drop these lines:

Dash.jl/.circleci/config.yml

Lines 30 to 33 in f0606e0

	- run:
	name: 🔎 Unit tests
	command: |
	julia test/ci_prepare.jl

Dash.jl/test/ci_prepare.jl

Line 11 in f0606e0

Pkg.test("Dash", coverage=true)

and have the CircleCI workflow be used just for the integration (percy) tests.

[etpinard]

Testing on Julia 1.3 leads to

We should probably update

Dash.jl/Project.toml

Line 39 in f0606e0

julia = "1.3"

to match the PlotlyBase.jl compat

[etpinard]

Hmm, I'll need to figure out why the final step of the CircleCI workflow is failing

[mind6]

As discussed in #175 (comment), I think it would be easier to run the Julia ] test for different Julia versions inside a Github workflow instead of inside the plotly/julia:ci docker container.

Running Julia tests inside Github workflows is fairly easy now thanks to the julia-actions organisation. This should make it much easier to maintain the list of tested Julia versions for Dash.jl. It's much easier to patch a yaml file than updating a docker image, right? 😛

I'm thinking we could also drop these lines:

Dash.jl/.circleci/config.yml

Lines 30 to 33 in f0606e0

	- run:
	name: 🔎 Unit tests
	command: |
	julia test/ci_prepare.jl

Dash.jl/test/ci_prepare.jl

Line 11 in f0606e0

Pkg.test("Dash", coverage=true)

and have the CircleCI workflow be used just for the integration (percy) tests.

The github actions seem quite nice. Don't know anything about CircleCI/percy hope it works out.

[etpinard]

We have passing tests 🎉 - merging!