feat: async fn in trait, supported since Rust v1.75

- https://blog.rust-lang.org/2023/12/21/async-fn-rpit-in-traits.html

BREAKING CHANGE: MSRV v1.75

Author: zonyitoo

.github/workflows/build-msrv.yml

@@ -28,9 +28,9 @@ jobs:
       - name: Install Rust
         run: |
           rustup set profile minimal
-          rustup toolchain install 1.74
-          rustup default 1.74
-          rustup override set 1.74
+          rustup toolchain install 1.75
+          rustup default 1.75
+          rustup override set 1.75
       - name: Build with All Features Enabled (Unix)
         if: ${{ runner.os == 'Linux' || runner.os == 'macOS' }}
         run: cargo build --verbose --features "full-extra local-flow-stat utility-url-outline"