fix(did-resolver): need to prefix check content-type

did-resolver/src/lib.rs

···
             .await?
             .error_for_status()?;
 
-        if let Some(ct) = res.headers().get(CONTENT_TYPE) {
-            if ct != "text/plain" {
+        if let Some(ct) = res
+            .headers()
+            .get(CONTENT_TYPE)
+            .and_then(|ct| ct.to_str().ok())
+        {
+            if !ct.starts_with("text/plain") {
                 return Ok(None);
             }
         }