v1.2.1

• Added HR Layout
• Added binaries for DIY versions

Note: USBNova_mkII_1.2.1.uf2 works for both USB Nova mkII (USB-A) and USB Nova mkII (USB-C).
For the old USB Nova (based on the ATSAMD21 with 4MB), use USBNova_mkI_1.2.1.uf2.