Add git to Dockerfile

[dplewis]

The push adapter now uses a node-apn fork. This PR adds git to the build to pull the fork down.

I'm not a docker expert. Any feedback would be great.

[TomWFox]

I have no idea about docker, so I really don't feel qualified to review this. @davimacedo could you take a look?

[dplewis]

@TomWFox If you look at the file there are 2 build phases. The first build phase adds git, I just copied it down to the release build.

[codecov]

Codecov Report

Merging #5861 into master will decrease coverage by 0.58%.
The diff coverage is n/a.

@@            Coverage Diff            @@
##           master   #5861      +/-   ##
=========================================
- Coverage   93.68%   93.1%   -0.59%     
=========================================
  Files         150     150              
  Lines       10616   10616              
=========================================
- Hits         9946    9884      -62     
- Misses        670     732      +62

Impacted Files	Coverage Δ
...dapters/Cache/RedisCacheAdapter/KeyPromiseQueue.js	0% <0%> (-95.46%)	⬇️
src/Adapters/Cache/RedisCacheAdapter/index.js	15.9% <0%> (-84.1%)	⬇️
src/Controllers/LoggerController.js	90.52% <0%> (-1.06%)	⬇️
src/RestWrite.js	93.56% <0%> (-0.34%)	⬇️
...dapters/Storage/Postgres/PostgresStorageAdapter.js	96.82% <0%> (-0.09%)	⬇️

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[TomWFox]

Ok, makes sense.