Install roave-backward-compatibility-check

Author: sebastianbergmann

.phive/phars.xml

@@ -2,4 +2,5 @@
 <phive xmlns="https://phar.io/phive">
   <phar name="php-cs-fixer" version="^2.16" installed="2.16.3" ___location="./tools/php-cs-fixer" copy="true"/>
   <phar name="psalm" version="^3.8" installed="3.11.5" ___location="./tools/psalm" copy="true"/>
+  <phar name="roave/backwardcompatibilitycheck" version="^4.4.0" installed="4.4.0" ___location="./tools/roave-backward-compatibility-check" copy="true"/>
 </phive>