Use bitcoin-kmp 0.27.0 and secp256k1-kmp 0.20.0 (#818)

Both libraries use kotlin 2.2.20.

Author: sstone

gradle/libs.versions.toml

@@ -4,8 +4,8 @@ kotlinx-coroutines = "1.10.2"
 kotlinx-datetime = "0.7.1"
 kotlinx-serialization = "1.9.0"
 ktor = "3.3.0"
-bitcoinkmp = "0.26.0" # when upgrading bitcoin-kmp, keep secpjnijvm in sync!
-secpjnijvm = "0.19.0"
+bitcoinkmp = "0.27.0" # when upgrading bitcoin-kmp, keep secpjnijvm in sync!
+secpjnijvm = "0.20.0"
 kermit = "2.0.8"
 slf4j = "2.0.17"