Not all html elements have an ending tag, for example:
<link rel="stylesheet" href="/roboto.css" />
In such cases, the current injection func injects the nonce after the forward slash, instead of before it
current result:
<link rel="stylesheet" href="/roboto.css" / nonce="abc123">

this patch corrects the behavior to:
<link rel="stylesheet" href="/roboto.css"  nonce="abc123"/>

Change fix method due to the way some tags are manipulated elsewhere.

For example, the csp playground contains:
<link rel="stylesheet" href="./linked.css" />

Which is then transformed into this prior to nonce injection:
<link rel="stylesheet" crossorigin href="/assets/index-BTAfrA7H.css">

There is no endTag, but the startTag no longer ends in `/>`. This is likely not ideal but this fix works around that issue.