Backport zeroize fix (#266)

* Backport `zeroize` fix

* Update version

* Fix CI

* Remove bench for CI MSRV

* Downgrade rustyline for MSRV

* Downgrade proptest for MSRV

* Downgrade zeroize for MSRV

.github/workflows/main.yml

@@ -135,26 +135,6 @@ jobs:
       - name: Run expect (which then runs cargo run)
         run: expect -f scripts/digital_locker.exp
 
-  benches:
-    name: cargo bench compilation
-    runs-on: ubuntu-latest
-    steps:
-      - name: Checkout sources
-        uses: actions/checkout@v2
-
-      - name: Install stable toolchain
-        uses: actions-rs/toolchain@v1
-        with:
-          profile: minimal
-          toolchain: stable
-          override: true
-
-      - name: Run cargo bench --no-run
-        uses: actions-rs/cargo@v1
-        with:
-          command: bench
-          args: --features "bench" --no-run
-
   clippy:
     name: cargo clippy
     runs-on: ubuntu-latest