remive meta[http-equiv="content-type"] tag

lib/single-file/single-file-core.js

@@ -366,7 +366,7 @@ this.SingleFileCore = this.SingleFileCore || (() => {
 		}
 
 		resetCharsetMeta() {
-			this.doc.querySelectorAll("meta[charset]").forEach(element => element.remove());
+			this.doc.querySelectorAll("meta[charset], meta[http-equiv=\"content-type\"]").forEach(element => element.remove());
 			const metaElement = this.doc.createElement("meta");
 			metaElement.setAttribute("charset", "utf-8");
 			this.doc.head.insertBefore(metaElement, this.doc.head.firstElementChild);