Fix typo

Author: shivammathur

extension/BuildPhpExtension/BuildPhpExtension.psd1

@@ -83,7 +83,7 @@
         'Get-BuildDirectory',
         'Get-Extension',
         'Get-ExtensionConfig',
-        'Get-ExtensionSource'
+        'Get-ExtensionSource',
         'Get-File',
         'Get-LibrariesFromConfig',
         'Get-OlderVsVersion',