Remove the wasm32-wasi target

Since [1], the `wasm32-wasi` target is no longer supported (replaced by
`wasm32-wasip1` and `wasm32-wasip2`). This has made it into the latest
nightly, so remove it from our testing.

[1]: rust-lang/rust#132562

(backport <rust-lang#4013>)
(cherry picked from commit a4d3ca8)

Cargo.toml

@@ -107,7 +107,6 @@ targets = [
     "thumbv7neon-unknown-linux-gnueabihf",
     "wasm32-unknown-emscripten",
     "wasm32-unknown-unknown",
-    "wasm32-wasi",
     "x86_64-apple-darwin",
     "x86_64-apple-ios",
     "x86_64-fortanix-unknown-sgx",

ci/build.sh

@@ -136,7 +136,6 @@ armv5te-unknown-linux-gnueabi \
 armv5te-unknown-linux-musleabi \
 i686-pc-windows-gnu \
 riscv64gc-unknown-linux-gnu \
-wasm32-wasi \
 x86_64-fortanix-unknown-sgx \
 x86_64-unknown-fuchsia \
 x86_64-pc-solaris \