docs: delete npm dependencies badge from README

[yoshinorin]

https://david-dm.org seems dead.

>curl -v https://david-dm.org
*   Trying 2606:4700::6810:f34e:443...
* Connected to david-dm.org (2606:4700::6810:f34e) port 443 (#0)
* schannel: disabled automatic use of client certificate
* ALPN: offers http/1.1
* ALPN: server accepted http/1.1
> GET / HTTP/1.1
> Host: david-dm.org
> User-Agent: curl/7.83.1
> Accept: */*
>
* Mark bundle as not supporting multiuse
< HTTP/1.1 504 Gateway Timeout
< Date: Tue, 30 Aug 2022 12:55:03 GMT
      <!DOCTYPE htm* Connection #0 to host david-dm.org left intact