🐛 Fix Transfer-Encoding field value to be case-insensitive

[Acamol]

Description

Fix Transfer-Encoding field value to be case-insensitive, in accordance with RFC-7230.

RFC-7230, section 4 states the following:
"All transfer-coding names are case-insensitive[...]"

Fix #743

Type of change

• Bug fix (a non-breaking change which fixes an issue)
• New feature (a non-breaking change which adds functionality)
• Breaking change (fix or feature that would cause existing functionality to not work as expected)
• Refactoring (a change which changes the current internal or external interface)
• This change requires a documentation update

How Has This Been Tested?

I have made a GET request to a server that responds with "Chunked" for the Transfer-Encoding field value, and saw that the response was decoded successfully. Also, made sure that old tests still pass.

Checklist:

• I have performed a self-review of my own code
• I have commented my code, particularly in hard-to-understand areas
• I have made corresponding changes to the documentation, if necessary
• My changes generate no new compiler warnings
• I have added tests that prove my fix is effective or that my feature works
• New and existing unit tests pass locally with my changes
• Inspect the bytecode viewer, including reasoning why

[codecov]

Codecov Report

Merging #744 into master will not change coverage.
The diff coverage is 0.00%.

@@            Coverage Diff            @@
##             master     #744   +/-   ##
=========================================
  Coverage     72.71%   72.71%           
  Complexity      301      301           
=========================================
  Files            61       61           
  Lines          1510     1510           
  Branches        205      205           
=========================================
  Hits           1098     1098           
  Misses          311      311           
  Partials        101      101           

Impacted Files	Coverage Δ	Complexity Δ
...lin/com/github/kittinunf/fuel/util/DecodeStream.kt	33.33% <0.00%> (ø)	0.00 <0.00> (ø)

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[kittinunf]

Thanks for the fix! :) @Acamol