BF: add spacebar to the valid keys

[superabe]

I found the spacebar is missing

Traceback (most recent call last):
  File "stimulus_show.py", line 40, in <module>
    event.globalKeys.add(key='space', func=pause)
  File "/usr/local/lib/python3.6/site-packages/psychopy/event.py", line 1090, in add
    raise ValueError('Unknown key specified: %s' % key)
ValueError: Unknown key specified: space

And adding the spacebar to the valid keys can fix this.

[codecov-io]

Codecov Report

Merging #2310 into master will decrease coverage by 0.01%.
The diff coverage is 100%.

@@            Coverage Diff             @@
##           master    #2310      +/-   ##
==========================================
- Coverage   42.88%   42.87%   -0.02%     
==========================================
  Files         221      221              
  Lines       38574    38574              
  Branches     6648     6648              
==========================================
- Hits        16543    16539       -4     
- Misses      20463    20466       +3     
- Partials     1568     1569       +1

Impacted Files	Coverage Δ
psychopy/event.py	60.64% <100%> (ø)	⬆️
psychopy/app/connections/news.py	46.66% <0%> (-8.89%)	⬇️

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[coveralls]

Coverage decreased (-0.02%) to 46.939% when pulling 8ae0e08 on superabe:fix-spacebar-missing-error into bbfd927 on psychopy:master.

[hoechenberger]

Thanks! Could you remove the comment please? It’s not necessary and seems a bit out of place here :)

[superabe]

Sure! Already removed.

[hoechenberger]

Thanks!

[peircej]

For future reference please use a commit message with one of BF: FF:... as listed in
https://www.psychopy.org/developers/repository.html#commit-messages

Without them we can't readily filter what should should not be included in bug-fix releases.

thanks for the contribution