Print '--seed=1234' rather than '--seed 1234' by default

[cben]

output before, when not specifying seed:

Run options: --seed 62153

after:

Run options: --seed=10759

Motivation

This is friendlier to re-running by copy-paste via Rake. These forms work:

env TESTOPTS='--seed=1234' rake test
rake test TESTOPTS='--seed=1234'

These forms with a space fail for me:

env TESTOPTS='--seed 1234' rake test
rake test TESTOPTS='--seed 1234'

with message like:

File does not exist: /home/me/kubeclient/1234

Of course this assumes one even discovers the rake TESTOPTS var...
Still, one less obstacle :-)

(I see from #564 you're not interested in minitest directly telling user Rake-specific hints how to use TESTOPTS.
Consider perhaps printing SEED=1234 hint instead of --seed hint? This works when running minitest directly, through Rake and probably through other runners.)

[zenspider]

I gotta say... I absolutely hate Rake's TestTask. I think it is just about the least usable thing out there. How about I replace it entirely with something that works well rather than applying bandaids to deal with rake?

https://github.com/seattlerb/hoe/blob/master/lib/minitest/test_task.rb

(this will be moved to minitest after running some laps)

[cben]

Friendly ping 👋
Any progress with replacing TestTask? IIUC the code you linked that would provide Minitest::TestTask, which will be opt-in, won't affect all the projects that followed current README's advice to use Rake::TestTask.
Any reason not to merge this tiny change?