Add tests for newline handling and fix support for windows.

[LilithHafner]

Should fix windows CI.
Waiting to push the fix till CI fails with the tests.
Closes #14 which was, in comparison to this, mucking around in the dark waiting for the lights to turn green.

[LilithHafner]

Ubunto nightly failed with a failure in the styled macro testset as expected (on 220bb5d)

[codecov]

Codecov Report

Merging #16 (9f29260) into main (63ff132) will increase coverage by 0.12%.
The diff coverage is 100.00%.

@@            Coverage Diff             @@
##             main      #16      +/-   ##
==========================================
+ Coverage   67.21%   67.33%   +0.12%     
==========================================
  Files           7        7              
  Lines         796      799       +3     
==========================================
+ Hits          535      538       +3     
  Misses        261      261              

Files	Coverage Δ
src/stylemacro.jl	71.69% <100.00%> (+0.26%)	⬆️

[LilithHafner]

And now all nightly tests pass! :)

[tecosaur]

Hmmm, I'm not sure we should actually test Julia's parsing of \<newline>.

StyledStrings.jl/test/runtests.jl

Lines 211 to 227 in 9b35f08

	normal = "abc\
	def"
	styled = styled"abc\
	def"
	@test normal == styled == "abcdef"
	normal = "abc\\ndef"
	styled = styled"abc\\ndef"
	@test normal == styled == "abc\\ndef"
	normal = eval(Meta.parse("\"abc\\\n \tdef\""))
	styled = eval(Meta.parse("styled\"abc\\\n \tdef\""))
	@test normal == styled == "abcdef"
	normal = eval(Meta.parse("\"abc\\\r\n def\""))
	styled = eval(Meta.parse("styled\"abc\\\r\n def\""))
	@test normal == styled == "abcdef"