Bump libsecp256k1 from v0.4.1 to v0.5.0

This release includes algorithmic improvements which increase the speed
of key generation and signing. At the same time, the binary size has
been reduced significantly.

Full changelog: https://github.com/bitcoin-core/secp256k1/blob/master/CHANGELOG.md#050---2024-05-06

The ABI is backward compatible with versions 0.4.x and 0.3.x, so no
python-bitcointx update is needed.

install.sh

@@ -324,9 +324,9 @@ libsecp256k1_build()
 
 libsecp256k1_install()
 {
-    secp256k1_version="0.4.1"
+    secp256k1_version="0.5.0"
     secp256k1_lib_tar="v$secp256k1_version.tar.gz"
-    secp256k1_lib_sha="31b1a03c7365dbce7aff4be9526243da966c58a8b88b6255556d51b3016492c5"
+    secp256k1_lib_sha="07934fde88c677abbc4d42c36ef7ef8d3850cd0c065e4f976f66f4f97502c95a"
     secp256k1_lib_url='https://github.com/bitcoin-core/secp256k1/archive/refs/tags'
     if ! dep_get "${secp256k1_lib_tar}" "${secp256k1_lib_sha}" "${secp256k1_lib_url}"; then
         return 1