Fix startup error in AWS Lambda

[lordkev]

Lambda has a similar issue with multiprocessing.Queue as OS X due to there being no /dev/shm, but it throws an OSError instead of NotImplementedError. Simple fix.

[lordkev]

Fixes #384

[codecov-io]

Codecov Report

Merging #405 into master will increase coverage by 0.19%.
The diff coverage is 0%.

@@            Coverage Diff             @@
##           master     #405      +/-   ##
==========================================
+ Coverage   90.43%   90.63%   +0.19%     
==========================================
  Files          43       43              
  Lines        2855     2915      +60     
==========================================
+ Hits         2582     2642      +60     
  Misses        273      273

Impacted Files	Coverage Δ
django_q/conf.py	74.75% <0%> (ø)	⬆️
django_q/tests/test_monitor.py	100% <0%> (ø)	⬆️
django_q/tests/test_admin.py	100% <0%> (ø)	⬆️
django_q/tests/test_commands.py	100% <0%> (ø)	⬆️
django_q/signing.py	100% <0%> (ø)	⬆️
django_q/tests/test_cluster.py	100% <0%> (ø)	⬆️
django_q/tests/test_cached.py	100% <0%> (ø)	⬆️
django_q/tests/test_scheduler.py	100% <0%> (ø)	⬆️
django_q/tasks.py	99.48% <0%> (+0.01%)	⬆️
django_q/models.py	97.45% <0%> (+0.04%)	⬆️
... and 7 more

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