Support Python v3.12, OSX Clang v15

• fixed Var::toDouble() type casting handling (credits to @dhoegerlETM dhoegerlETM for #3)
• more tests added
• fix github actions CI MACOS OSX + CLANG
• remove deprecated C API PyUnicode_AsUnicode() for support python 3.12 OSX Clang 15

What's Changed

• Fix build by @reefactor in #4

New Contributors

• @reefactor made their first contribution in #4

Full Changelog: 1.1.0...1.2.0