chore: single quote install crawlee with extras (#158)

### Description

- To avoid issues with `zsh` when using package names with extras
(`crawlee[beautifulsoup]`).
- [zsh: no matches found:
requests[security]](https://stackoverflow.com/questions/30539798/zsh-no-matches-found-requestssecurity).
- We encountered this issue with @souravjain540.

Author: vdusek

README.md

@@ -22,16 +22,16 @@ Visit our GitHub repository for more information [Crawlee on GitHub](https://git
 
 Crawlee is available as the [`crawlee`](https://pypi.org/project/crawlee/) PyPI package.
 
-```
+```bash
 pip install crawlee
 ```
 
 Additional, optional dependencies unlocking more features are shipped as package extras.
 
 If you plan to use `BeautifulSoupCrawler`, install `crawlee` with `beautifulsoup` extra:
 
-```
-pip install crawlee[beautifulsoup]
+```bash
+pip install 'crawlee[beautifulsoup]'
 ```
 
 ## Features