libwebp v1.3.2

What's Changed

• github: Bump Go versions by @bep in #9
• deps/libwebp132 take by @bep in #11
• a__cgo.go: we need libm on every Unix, not just Linux by @Artoria2e5 in #6

New Contributors

• @Artoria2e5 made their first contribution in #6

Full Changelog: v0.2.0...v0.3.0