style: consistent use of single quote over double quote

autoload/vivify.vim

@@ -2,8 +2,8 @@ let s:viv_url = 'http://localhost:' . ($VIV_PORT == '' ? '31622' : $VIV_PORT)
 
 " Note: nvim's jobstart isn't exactly a drop-in replacement for vim's job_start
 " See here: https://stackoverflow.com/questions/74999614/difference-between-vims-job-start-function-and-neovims-jobstart-functi
-if has("nvim")
-    let s:job_start = function("jobstart")
+if has('nvim')
+    let s:job_start = function('jobstart')
 
     " job is job_id as returned from jobstart()
     function! s:stdin_send_and_close(job, data)
@@ -18,7 +18,7 @@ else
         call ch_close_in(l:channel)
     endfunction
 
-    let s:job_start = function("job_start")
+    let s:job_start = function('job_start')
 endif
 
 function! s:post(data)
@@ -44,6 +44,6 @@ function! vivify#open()
     " Note: nvim's jobstart doesn't use these opt keys
     call s:job_start(
         \ ['viv', expand('%:p')->substitute(':', '\\:', 'g') . ':' . getpos('.')[1]],
-        \ {"in_io": "null", "out_io": "null", "err_io": "null"}
+        \ {'in_io': 'null', 'out_io': 'null', 'err_io': 'null'}
     \)
 endfunction