Release multiboot2-header-v0.2.0

What's Changed

• updated changelogs by @phip1611 in #104
• repo: add CI no_std check by @phip1611 in #101
• publicly announce the MSRV is 1.52.1. by @phip1611 in #106
• CI Fix: actually use different Rust versions by @phip1611 in #108
• Multiboot2 header builder restructuring by @phip1611 in #109
• multiboot2-header: remove packed(8) by @phip1611 in #112
• multiboot2-header: removed unused test_utils module by @phip1611 in #113
• multiboot2-header: prepare v0.2.0 by @phip1611 in #110

Full Changelog: multiboot2-v0.13.2...multiboot2-header-v0.2.0