make temporal codecs immune to locale

[tpolecat]

A user discovered that temporal codecs with an era as part of their format don't work in some locales (es_CO specifically but there are likely others). This fixes the locale to Locale.US in the DateTimeFormatters used by the codecs, which should be ok because we're fixing the date style to ISO, MDY during session startup and have declared in the doc that if you change it you're in trouble.

[codecov-commenter]

Codecov Report

Merging #232 into master will increase coverage by 0.44%.
The diff coverage is 100.00%.

@@            Coverage Diff             @@
##           master     #232      +/-   ##
==========================================
+ Coverage   83.56%   84.01%   +0.44%     
==========================================
  Files         107      107              
  Lines        1229     1251      +22     
  Branches       16       22       +6     
==========================================
+ Hits         1027     1051      +24     
+ Misses        202      200       -2     

Impacted Files	Coverage Δ
modules/core/src/main/scala/Decoder.scala	100.00% <100.00%> (ø)
...les/core/src/main/scala/codec/TemporalCodecs.scala	87.27% <100.00%> (+6.19%)	⬆️
...ore/src/main/scala/net/AbstractMessageSocket.scala	83.33% <0.00%> (+33.33%)	⬆️

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