Siepic-ebeam-pdk

What's Changed
* Changed up convention in thermo_optic examples to use opt_in labels on GCs and to only label top electrical pad without any _G by PetervandenDoel in https://github.com/SiEPIC/SiEPIC_EBeam_PDK/pull/290
* Update Dockerfile by seanlam-ece in https://github.com/SiEPIC/SiEPIC_EBeam_PDK/pull/291
* Create SWG_Ring.py by bcohenkl55 in https://github.com/SiEPIC/SiEPIC_EBeam_PDK/pull/293
* Create Silicon Nitride EBeam_GC_SiN_1310_8deg.py by Hang-Bobby-Zou in https://github.com/SiEPIC/SiEPIC_EBeam_PDK/pull/292, https://github.com/SiEPIC/SiEPIC_EBeam_PDK/pull/298
* submission of the pbs_1550_eskid by AndrazDebevc in https://github.com/SiEPIC/SiEPIC_EBeam_PDK/pull/295

- xsection (cross section) fix. removed xsection code from this package, and added dependancy to https://klayoutmatthias.github.io/xsection/

- xsection (cross section) fix. removed xsection code from this package, and added dependancy to https://klayoutmatthias.github.io/xsection/

* added a Design for Test verification to check that the grating couplers are at least 60 microns apart. This is in DFT.xml, minimum-gc-spacing = 60

- updates and bug fixes in several PCells

- EBeam_Beta: ebeam_y_1310 fix text label