Disable core-time feautre due to iana-time-zone incompatibility

```
6 | / compile_error!(
7 | |     "iana-time-zone is currently implemented for Linux, Window, MacOS, FreeBSD, NetBSD, \
8 | |     OpenBSD, Dragonfly, WebAssembly (browser), iOS, Illumos, Android, AIX, Solaris and Haiku.",
9 | | );
  | |_^
```

See:

- strawlab/iana-time-zone#130

.github/workflows/ci.yaml

@@ -137,9 +137,7 @@ jobs:
         run: cargo clippy --workspace --all-features --all-targets
 
       - name: Lint with Clippy on emscripten target
-        run: |
-          sed -i '/"core-time"/s/^/  # /' playground/Cargo.toml
-          cargo clippy --workspace --all-features --all-targets --target wasm32-unknown-emscripten
+        run: cargo clippy --workspace --all-features --all-targets --target wasm32-unknown-emscripten
 
   ruby:
     name: Lint and format Ruby

playground/Cargo.toml

@@ -29,7 +29,6 @@ features = [
   "core-math-full",
   "core-random",
   "core-regexp",
-  "core-time",
   "output-strategy-capture",
   "stdlib-full",
 ]