use best zip compression

[jftuga]

This patch updates build-lambda-zip such that the max compression level is used instead of the default zip compression level.

[codecov-io]

Codecov Report

Merging #283 into master will not change coverage.
The diff coverage is n/a.

@@           Coverage Diff           @@
##           master     #283   +/-   ##
=======================================
  Coverage   74.51%   74.51%           
=======================================
  Files          13       13           
  Lines         624      624           
=======================================
  Hits          465      465           
  Misses        121      121           
  Partials       38       38           

---

Continue to review full report at Codecov.

Legend - Click here to learn more
Δ = absolute <relative> (impact), ø = not affected, ? = missing data
Powered by Codecov. Last update fc7add7...018aad8. Read the comment docs.

[codecov-commenter]

Codecov Report

Merging #283 into master will not change coverage.
The diff coverage is n/a.

@@           Coverage Diff           @@
##           master     #283   +/-   ##
=======================================
  Coverage   74.60%   74.60%           
=======================================
  Files          13       13           
  Lines         638      638           
=======================================
  Hits          476      476           
  Misses        123      123           
  Partials       39       39           

---

Continue to review full report at Codecov.

Legend - Click here to learn more
Δ = absolute <relative> (impact), ø = not affected, ? = missing data
Powered by Codecov. Last update 26aa364...9dad1fb. Read the comment docs.

[bmoffatt]

Note: I added a test in #307 that can log how this change affects the .zip file

[bmoffatt]

I accidentally hit "close" instead of "merge" - but I see that the source branch no longer exists. Feel free to re-submit this PR