fix: bump pocket-ic crate to 13.0.0 to match server binary

Local PocketIC server binary is v13.0.0 but the workspace crate was
pinned to 12.0.0 (which rejects >=13). Bumping to 13.0.0 resolves the
version mismatch.

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

Author: Web3NL

Cargo.lock

@@ -29,7 +29,7 @@ ic-ledger-types = "0.16.0"
 include_dir = "0.7.4"
 icrc-ledger-types = "0.1.12"
 mime_guess = "2.0.5"
-pocket-ic = "12.0.0"
+pocket-ic = "13.0.0"
 serde = { version = "1.0.228", features = ["derive"] }
 serde_cbor = "0.11.2"
 serde_json = "1.0.149"