Bump phpseclib/phpseclib from 2.0.47 to 2.0.53

Bumps [phpseclib/phpseclib](https://github.com/phpseclib/phpseclib) from 2.0.47 to 2.0.53.
- [Release notes](https://github.com/phpseclib/phpseclib/releases)
- [Changelog](https://github.com/phpseclib/phpseclib/blob/master/CHANGELOG.md)
- [Commits](phpseclib/phpseclib@2.0.47...2.0.53)

---
updated-dependencies:
- dependency-name: phpseclib/phpseclib
  dependency-version: 2.0.53
  dependency-type: direct:production
...

Signed-off-by: dependabot[bot] <support@github.com>

Author: dependabot[bot]

composer.json

@@ -13,7 +13,7 @@
         "fuel/parser": "1.8.*",
         "fuelphp/upload": "2.0.6",
         "monolog/monolog": "^1.18",
-        "phpseclib/phpseclib": "2.0.47",
+        "phpseclib/phpseclib": "2.0.53",
         "michelf/php-markdown": "1.7.0",
         "thunderer/shortcode": "*",
         "mobiledetect/mobiledetectlib": "*",