dotenv: fix prompt newline

plugins/dotenv/dotenv.plugin.zsh

 source_env() {
   if [[ -f $ZSH_DOTENV_FILE ]]; then
-
     if [ "$ZSH_DOTENV_PROMPT" != "false" ]; then
       # confirm before sourcing file
       local confirmation
+      # print same-line prompt and output newline character if necessary
       echo -n "dotenv: source '$ZSH_DOTENV_FILE' file in the directory? (Y/n) "
-      if read -k 1 confirmation && [[ $confirmation = [nN] ]]; then
+      read -k 1 confirmation; [[ "$confirmation" != $'\n' ]] && echo
+      # only bail out if confirmation character is n
+      if [[ "$confirmation" = [nN] ]]; then
         return
       fi
     fi