Fix #1154: add safety checks to parse 400 error responses

[leplatrem]

Since I don't know if the original code was supposed to support specific response bodies, I decided to keep the original behaviour and add safety checks for the responses that we receive from Jira in 400 responses.

[leplatrem]

According to this https://developer.atlassian.com/server/jira/platform/rest-apis/#error-responses the errors field is just dict[str, str]

[leplatrem]

build/temp.linux-x86_64-cpython-311/ast27/Custom/typed_ast.o
      In file included from ast27/Custom/typed_ast.c:3:
      ast27/Custom/../Include/compile.h:5:10: fatal error: code.h: No such file or directory
          5 | #include "code.h"
            |          ^~~~~~~~
      compilation terminated.
      error: command '/usr/bin/x86_64-linux-gnu-gcc' failed with exit code 1
      [end of output]
  
  note: This error originates from a subprocess, and is likely not a problem with pip.
  ERROR: Failed building wheel for typed-ast
ERROR: Could not build wheels for typed-ast, which is required to install pyproject.toml-based projects
mypy: FAIL ✖ in 2.78 seconds

@gonchik are pull-requests broken? this error doesn't really related to my changes...

[gonchik]

Thanks! for the PR.
Yes, PR was broken as I created 3.11 env and did not tested properly for docker of 20.04 installation