Bump minimum PHP version requirement to 5.4

Author: jmikola

bin/package.xml.in

@@ -46,7 +46,7 @@ necessary to build a fully-functional MongoDB driver.
  <dependencies>
   <required>
    <php>
-    <min>5.3.0</min>
+    <min>5.4.0</min>
     <max>5.99.99</max>
    </php>
    <pearinstaller>