Work around '#' escaping bug in bip21 crate

bip21 dependency temporarily specified to use bugfix PR branch

The `pj` parameter of the BIP 21 URL is itself a URL which contains a
fragment.

This is not escaped by bip21 during serialization, which according to
RFC 3986 truncates the `pj` parameter, making everything that follows
part of the fragment.

Deserialization likewise ignores #, parsing it as part of the value
which round trips with the incorrect serialization behavior.

Temporarily depend on bugfix pr branch for bip21

payjoin/Cargo.toml

@@ -25,7 +25,7 @@ danger-local-https = ["io", "reqwest/rustls-tls", "rustls"]
 
 [dependencies]
 bitcoin = { version = "0.32.2", features = ["base64"] }
-bip21 = "0.5.0"
+bip21 = { git = "https://github.com/Kixunil/bip21.git", rev = "refs/pull/26/head" }
 hpke = { package = "bitcoin-hpke", version = "0.13.0", optional = true }
 log = { version = "0.4.14"}
 http = { version = "1", optional = true }

payjoin/src/uri/url_ext.rs

@@ -129,9 +129,20 @@ mod tests {
     #[test]
     fn test_valid_v2_url_fragment_on_bip21() {
         let uri = "bitcoin:12c6DSiU4Rq3P4ZxziKxzrL5LmMBrzjrJX?amount=0.01\
-                   &pj=https://example.com\
-                   #ohttp%3DAQO6SMScPUqSo60A7MY6Ak2hDO0CGAxz7BLYp60syRu0gw";
-        let uri = Uri::try_from(uri).unwrap().assume_checked().check_pj_supported().unwrap();
-        assert!(uri.extras.endpoint().ohttp().is_some());
+                   &pj=https://example.com/\
+                   %23ohttp%3DAQO6SMScPUqSo60A7MY6Ak2hDO0CGAxz7BLYp60syRu0gw\
+                   &pjos=0";
+        let pjuri = Uri::try_from(uri).unwrap().assume_checked().check_pj_supported().unwrap();
+
+        assert!(pjuri.extras.endpoint().ohttp().is_some());
+        assert_eq!(format!("{}", pjuri), uri);
+
+        let reordered = "bitcoin:12c6DSiU4Rq3P4ZxziKxzrL5LmMBrzjrJX?amount=0.01\
+                   &pjos=0&pj=https://example.com/\
+                   %23ohttp%3DAQO6SMScPUqSo60A7MY6Ak2hDO0CGAxz7BLYp60syRu0gw";
+        let pjuri =
+            Uri::try_from(reordered).unwrap().assume_checked().check_pj_supported().unwrap();
+        assert!(pjuri.extras.endpoint().ohttp().is_some());
+        assert_eq!(format!("{}", pjuri), uri);
     }
 }