Bump elements dependency

[stevenroose]

I tried to bump the elements-dependency, but then somehow the linking of the secp symbols failed. I don't really understand why, I see that the new elements, uses a different version of secp256k1-sys but if both versions are there, the symbols of the 0.4.1 version should also be available.

Can someone reproduce this?

The only diff I have is

diff --git a/Cargo.toml b/Cargo.toml
index 4def62f..37d97fd 100644
--- a/Cargo.toml
+++ b/Cargo.toml
@@ -7,7 +7,7 @@ edition = "2018"

 [dependencies]
 elements-consensus-sys = { path = "./elements-consensus-sys" }
-elements = "0.18"
+elements = "0.23"

 [dev-dependencies]
 hex-literal = "0.3"
diff --git a/src/lib.rs b/src/lib.rs
index c6bb011..f4043c5 100644
--- a/src/lib.rs
+++ b/src/lib.rs
@@ -108,7 +108,7 @@ mod tests {
     fn index_out_of_bounds_protects_from_unreachable_1() {
         let transaction = Transaction {
             version: 2,
-            lock_time: 0,
+            lock_time: elements::LockTime::ZERO,
             input: Vec::new(),
             output: Vec::new(),
         };