Fix Vint version detection (#5138)

* Ignore python warnings during 'vint --version' call

* Update Vint tests

ale_linters/vim/vint.vim

@@ -58,7 +58,7 @@ call ale#linter#Define('vim', {
 \   'command': {buffer -> ale#semver#RunWithVersionCheck(
 \       buffer,
 \       ale#Var(buffer, 'vim_vint_executable'),
-\       '%e --version',
+\       'PYTHONWARNINGS=ignore %e --version',
 \       function('ale_linters#vim#vint#GetCommand'),
 \   )},
 \   'callback': 'ale_linters#vim#vint#Handle',

test/linter/test_vint.vader

@@ -10,7 +10,7 @@ After:
 
 Execute(The default command should be correct):
   AssertLinter 'vint', [
-  \ ale#Escape('vint') .' --version',
+  \ 'PYTHONWARNINGS=ignore '. ale#Escape('vint') .' --version',
   \ ale#Escape('vint') .' -s --no-color' . b:common_flags . ' %t',
   \]
 
@@ -18,7 +18,7 @@ Execute(The executable should be configurable):
   let g:ale_vim_vint_executable = 'foobar'
 
   AssertLinter 'foobar', [
-  \ ale#Escape('foobar') .' --version',
+  \ 'PYTHONWARNINGS=ignore '. ale#Escape('foobar') .' --version',
   \ ale#Escape('foobar') .' -s --no-color' . b:common_flags . ' %t',
   \]