This is a maintenance release. The code contains no functional change.
Satisfied users of version 0.63 can skip this update.

• Add : Contributing guidelines are now listed in the new
  CONTRIBUTING file.
  
• Fix : [RT #151104] : fix for t/18-opinfo.t broken under blead
  Some optimization in core made t/18-opinfo.t fail since perl
  5.39.7, but that was reverted before 5.40 was released.
  This fix will make this test pass even when the optimization
  is reinstantiated after release freeze.
  Thanks David Mitchell for reporting and providing a fix.