Ignore RFC 3986 fragments in BIP 21 URIs

Although behavior for when encountering RFC 3986 fragments in BIP 21
URIs is not specified, according to RFC 3986 it is unambiguously not
query data and therefore should be excluded from BIP 21 query
parameters.

[WIP] squash with parent commits:
6a1f2be failing test that fragments aren't parsed for params
ea534d7 failing test that fragment separator is ignored

src/de.rs

@@ -42,6 +42,16 @@ impl<'a, T: DeserializeParams<'a>> Uri<'a, bitcoin::address::NetworkUnchecked, T
         let mut label = None;
         let mut message = None;
         if let Some(params) = params {
+            // [RFC 3986 § 3.4](https://www.rfc-editor.org/rfc/rfc3986#section-3.4):
+            //
+            // > The query component is indicated by the first question
+            // > mark ("?") character and terminated by a number sign ("#") character
+            // > or by the end of the URI.
+            let params = match params.find('#') {
+                Some(pos) => &params[..pos],
+                None => params,
+            };
+
             for param in params.split('&') {
                 let pos = param
                     .find('=')