update klayout to 0.27.3

0.27.3 contains bug fixes on DRC and LVS.
A complete list of changes can be found at https://www.klayout.de/development.html

As before, open a few GDS files (kB to GB in size) and browse the layout. Open Help->About and check it ruby/python bindings are present in the `Build options'.

• Open a few GDS files (kB to GB in size) and browse the layout.
• Open Help->About and check it ruby/python bindings are present in the Build options and ~20 .so files are present in Binary Extensions.
• Start python3, import klayout and pya modules.