v1.3.0 Release

What's Changed

• Use R CMD CONFIG to detect compiler by @andrjohns in #56
• Testing quickjs-ng as base by @andrjohns in #57
• Update more non-API C calls by @andrjohns in #58
• Update to new exported QuickJS APIs by @andrjohns in #59
• Backport QuickJS-NG fixes by @andrjohns in #62
• Add additional jsvalue conversion helpers by @andrjohns in #63
• Use updated cross-platform docker images by @andrjohns in #64

Full Changelog: v1.2.2...v1.3.0