Append libpmg123-dev dependency to the readme.

README.md

@@ -44,13 +44,14 @@ The following dependencies are also required:
 | jq             | jq               |
 | gcc            | gcc              |
 | pkg-config     | pkg-config       |
+| libmpg123      | libmpg123-dev    |
 
 Users of Debian-based systems (e.g. Ubuntu) can simply run the
 following to install the required dependencies:
 
 ```shell
 # apt-get update
-# apt-get install -y git make jq gcc pkg-config
+# apt-get install -y git make jq gcc pkg-config libmpg123-dev
 ```
 
 Alternatively, users can try using the automated script under `contrib`