build(deps): Remove paragonie/sodium_compat dependency

Since the package requires PHP 7.3+, and libsodium has been available
in PHP core since 7.2, the paragonie/sodium_compat polyfill is redundant.
The sodium extension is already required by the code that uses
sodium_crypto_secretbox functions.

Fixes #400

Author: L3o-pold

composer.json

@@ -8,8 +8,7 @@
         "ext-curl": "*",
         "ext-json": "*",
         "guzzlehttp/guzzle": "^7.2",
-        "psr/log": "^1.0|^2.0|^3.0",
-        "paragonie/sodium_compat": "^1.6|^2.0"
+        "psr/log": "^1.0|^2.0|^3.0"
     },
     "require-dev": {
         "phpunit/phpunit": "^9.3",