fix: php: handle deps without composer.json

Without composer.json in the root of a package,
composer will ignore the dependency, this is issue if
for example npm dependencies are managed via composer.
(yiisoft/yii2 2.0.46)

src/subsystems/php/builders/granular-php/default.nix

@@ -176,6 +176,12 @@
             echo {\"name\":\"${name}\"} > composer.json
           fi
 
+          # create composer.json if does not exist
+          if [ ! -f composer.json ]
+          then
+            echo {\"name\":\"${name}\"} > composer.json
+          fi
+
           # remove composer.lock if exists
           rm -f composer.lock