Inkscape build toolset v0.64

Most notable changes in this release are

• use Big Sur as build host

build info

• workflow run release #74
• sha256 is c604dd640aa789edafa90a89b0c90aa866303dafcca219198a48c71805a2243c
• important parameters

  SYS_MACOS_VER = 11.6.5
  SYS_SDK_VER = 10.13
  VERSION = 0.64
  VER_DIR = /Users/Shared/work/mibap-0.64
  WRK_DIR = /Users/Shared/work