AutosuggestTextarea: inputRef --> ref

For upgrade to react-textarea-autosize v8

app/soapbox/components/autosuggest_textarea.js

@@ -228,7 +228,7 @@ export default class AutosuggestTextarea extends ImmutablePureComponent {
             <span style={{ display: 'none' }}>{placeholder}</span>
 
             <Textarea
-              inputRef={this.setTextarea}
+              ref={this.setTextarea}
               className='autosuggest-textarea__textarea'
               disabled={disabled}
               placeholder={placeholder}