Fix error when single quote entered into buffer

Error looked something like:

```
% echo 'f(zpty):8: unmatched '
_zsh_autosuggest_capture_completion:zpty:9: no such pty command: zsh_autosuggest_completion_pty
_zsh_autosuggest_capture_completion:zpty:14: no such pty command: zsh_autosuggest_completion_pty
_zsh_autosuggest_capture_completion:zpty:21: no such pty command: zsh_autosuggest_completion_pty
```

According to `man zshmodules`, the args to `zpty` are "concatenated with
spaces between, then executed as a command, as if passed to the eval
builtin." So we need to escape the `$` so that `$1` is passed to eval
instead of the value of `$1`.

src/strategies/completion.zsh

@@ -94,7 +94,7 @@ _zsh_autosuggest_capture_completion() {
 	if zle; then
 		zpty $ZSH_AUTOSUGGEST_COMPLETIONS_PTY_NAME zle autosuggest-capture-completion
 	else
-		zpty $ZSH_AUTOSUGGEST_COMPLETIONS_PTY_NAME "_zsh_autosuggest_capture_buffer '$1'"
+		zpty $ZSH_AUTOSUGGEST_COMPLETIONS_PTY_NAME _zsh_autosuggest_capture_buffer "\$1"
 		zpty -w $ZSH_AUTOSUGGEST_COMPLETIONS_PTY_NAME $'\t'
 	fi
 

zsh-autosuggestions.zsh

@@ -593,7 +593,7 @@ _zsh_autosuggest_capture_completion() {
 	if zle; then
 		zpty $ZSH_AUTOSUGGEST_COMPLETIONS_PTY_NAME zle autosuggest-capture-completion
 	else
-		zpty $ZSH_AUTOSUGGEST_COMPLETIONS_PTY_NAME "_zsh_autosuggest_capture_buffer '$1'"
+		zpty $ZSH_AUTOSUGGEST_COMPLETIONS_PTY_NAME _zsh_autosuggest_capture_buffer "\$1"
 		zpty -w $ZSH_AUTOSUGGEST_COMPLETIONS_PTY_NAME $'\t'
 	fi