base64-0.5.1

A point release that introduces some improvements and fixes some bugs. Included in this release:

• #105: Fix out-of-bounds access in test
• #107: CI: upgrade deprecated Ubuntu image
• #104: AVX2: enc: add inline asm codepath
• #108: AVX: enc: add inline asm codepath
• #102: Enable avx512 support for base64 encoding
• #109: SSSE3: enc: add inline asm codepath
• #110: Fix i686 builds
• #112: chore(ci): run static/dynamic analysis
• #111: bug: out-of-bounds read when using inline assembly code path
• #115: bin/base64: modernize the demo program
• #118: enc: asm: add memory and flags as clobbers
• #121: Fix AVX detection