[v3] Release 3.0.0.alpha.1

[jhamman]

We've landed some important fixes to the v3 branch in the past two weeks. I'd like us to make another alpha release soon (perhaps on Monday July 8th?).

The following PRs seem close and good candidates to get in before the next release:

• Initial GPU support #1967
• Use config to select implementation #1982
• fix file modes #2000
• test: check that store, array, and group classes are serializable  #2006

Plus @dstansby has some good additions to the docs in flight:

• Autogenerate all API docs #2002
• Fix low contrast in dark theme h3 headings #2003

@brokkoli71, @normanrz, @dstansby, @d-v-b, and @akshaysubr - does this sound reasonable and/or am I missing anything here?

[dstansby]

👍 sounds good to me

[jhamman]

I'm going to close this now that we are making weekly alpha releases. 3.0.0.alpha2 will go out later today.