Fix parsing of quoted cookie values

[theawless]

I hit this bug in my project where the cookie value was "" - just two quote characters.
On checking the code, I figured that this bug might exist for all quoted cookie values.

The test case I had written for quoted cookie values was failing with this error:

failures:
---- cookies::cookie::tests::parse_simple::_r_foo_bar_ stdout ----
thread 'cookies::cookie::tests::parse_simple::_r_foo_bar_' panicked at 'assertion failed: `(left == right)`
  left: `"ba"`,
 right: `"bar"`', src\cookies\cookie.rs:310:9
note: run with `RUST_BACKTRACE=1` environment variable to display a backtrace

Previously one extra character was getting stripped from the end.
This commit fixes the index while stripping the end quote.

[codecov]

Codecov Report

Merging #288 (6fb0c95) into master (18ee975) will increase coverage by 0.04%.
The diff coverage is 100.00%.

@@            Coverage Diff             @@
##           master     #288      +/-   ##
==========================================
+ Coverage   72.79%   72.83%   +0.04%     
==========================================
  Files          51       51              
  Lines        2727     2728       +1     
==========================================
+ Hits         1985     1987       +2     
+ Misses        742      741       -1     

Impacted Files	Coverage Δ
src/cookies/cookie.rs	87.20% <100.00%> (+0.90%)	⬆️

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[sagebind]

Thanks for finding and fixing this bug, this could be pretty annoying to run into. I see you also updated the unit tests too! ❤️

[sagebind]

This is now available in the 1.0.3 release! Sorry about the delay, we were waiting for a third-party dependency to fix a compile error introduced by a new syn release published.