Minor performance improvement

Dependencies

• [2] OP6SVMOD Resetting history

Change contents

• replacement in sanakirja-core/src/btree/page.rs at line 624
  [2.29866]→[2.29866:29905](∅→∅)
  − data -= data % (align as u16);
  [2.29866]

  [2.29905]
  + data -= data & ((align - 1) as u16);