Update rust-toolchain and proptest

It is required for stabilized subslice patterns.

proptest 0.9.6 fixes compatibility with the latest rustc nightly.

.github/workflows/code-quality.yml

@@ -10,7 +10,7 @@ jobs:
       - uses: actions-rs/toolchain@v1
         with:
           profile: minimal
-          toolchain: nightly-2019-11-06
+          toolchain: nightly-2020-04-10
           override: true
       - uses: actions-rs/cargo@v1
         with:
@@ -25,7 +25,7 @@ jobs:
       - uses: actions-rs/toolchain@v1
         with:
           profile: minimal
-          toolchain: nightly-2019-11-06
+          toolchain: nightly-2020-04-10
           override: true
       - run: rustup component add rustfmt
       - uses: actions-rs/cargo@v1
@@ -39,10 +39,10 @@ jobs:
       - uses: actions/checkout@v1
       - uses: actions-rs/toolchain@v1
         with:
-            toolchain: nightly-2019-11-06
+            toolchain: nightly-2020-04-10
             components: clippy
             override: true
       - uses: actions-rs/clippy-check@v1
         with:
           token: ${{ secrets.GITHUB_TOKEN }}
-          args: --all-features
+          args: --all-features