chore(ci): add 1.75, test asynch and use nightly for linting and check

Signed-off-by: Lachezar Lechev <[email protected]>

.github/workflows/ci.yml

@@ -12,10 +12,10 @@ jobs:
     name: Lints and checks
     runs-on: ubuntu-latest
     steps:
-      - uses: actions/checkout@v3
+      - uses: actions/checkout@v4
         with:
           submodules: true
-      - uses: dtolnay/rust-toolchain@stable
+      - uses: dtolnay/rust-toolchain@nightly
         with:
             components: rustfmt, clippy
 
@@ -35,14 +35,17 @@ jobs:
           - beta
           - nightly
           - 1.65 # MSRV
+          - 1.75 # `async_fn_in_trait` + `impl_trait_projections` stabilised
 
     steps:
-      - uses: actions/checkout@v3
+      - uses: actions/checkout@v4
 
       - uses: dtolnay/rust-toolchain@master
         with:
           toolchain: ${{ matrix.rust }}
 
       - run: cargo build
       - run: cargo test
+      - run: cargo build -F asynch
+      - run: cargo test -F asynch