elliptic-curve: bump MSRV to 1.56

The RustCrypto/formats repo was bumped to Rust 2021 edition, and some of
those crates (e.g. `der`, `sec1`) are hard dependencies for the
`elliptic-curve` crate:

RustCrypto/formats#136

This is a corresponding Rust 2021 edition bump for the `elliptic-curve`
crate, as well as the omnibus `crypto` crate whose MSRV is determined by
the highest MSRV crate in this repo.

.github/workflows/crypto.yml

@@ -22,7 +22,7 @@ jobs:
     strategy:
       matrix:
         rust:
-          - 1.55.0 # MSRV
+          - 1.56.0 # MSRV
           - stable
         target:
           - thumbv7em-none-eabi
@@ -43,7 +43,7 @@ jobs:
     strategy:
       matrix:
         rust:
-          - 1.55.0 # MSRV
+          - 1.56.0 # MSRV
           - stable
     steps:
     - uses: actions/checkout@v1
@@ -55,3 +55,35 @@ jobs:
     - run: cargo test --no-default-features --release
     - run: cargo test --release
     - run: cargo test --all-features --release
+
+  clippy:
+    runs-on: ubuntu-latest
+    steps:
+      - uses: actions/checkout@v1
+      - uses: actions-rs/toolchain@v1
+        with:
+          toolchain: 1.56.0
+          components: clippy
+          override: true
+          profile: minimal
+      - run: cargo clippy --all --all-features -- -D warnings
+
+  rustfmt:
+    runs-on: ubuntu-latest
+    steps:
+      - name: Checkout sources
+        uses: actions/checkout@v1
+
+      - name: Install stable toolchain
+        uses: actions-rs/toolchain@v1
+        with:
+          toolchain: stable
+          components: rustfmt
+          override: true
+          profile: minimal
+
+      - name: Run cargo fmt
+        uses: actions-rs/cargo@v1
+        with:
+          command: fmt
+          args: --all -- --check

.github/workflows/elliptic-curve.yml

@@ -22,7 +22,7 @@ jobs:
     strategy:
       matrix:
         rust:
-          - 1.55.0 # MSRV
+          - 1.56.0 # MSRV
           - stable
         target:
           - thumbv7em-none-eabi
@@ -54,7 +54,7 @@ jobs:
     strategy:
       matrix:
         rust:
-          - 1.55.0 # MSRV
+          - 1.56.0 # MSRV
           - stable
           - nightly
     steps:
@@ -67,3 +67,35 @@ jobs:
     - run: cargo test --no-default-features
     - run: cargo test
     - run: cargo test --all-features
+
+  clippy:
+    runs-on: ubuntu-latest
+    steps:
+      - uses: actions/checkout@v1
+      - uses: actions-rs/toolchain@v1
+        with:
+          toolchain: 1.56.0
+          components: clippy
+          override: true
+          profile: minimal
+      - run: cargo clippy --all --all-features -- -D warnings
+
+  rustfmt:
+    runs-on: ubuntu-latest
+    steps:
+      - name: Checkout sources
+        uses: actions/checkout@v1
+
+      - name: Install stable toolchain
+        uses: actions-rs/toolchain@v1
+        with:
+          toolchain: stable
+          components: rustfmt
+          override: true
+          profile: minimal
+
+      - name: Run cargo fmt
+        uses: actions-rs/cargo@v1
+        with:
+          command: fmt
+          args: --all -- --check

.github/workflows/workspace.yml

@@ -16,7 +16,7 @@ jobs:
     - uses: actions/checkout@v1
     - uses: actions-rs/toolchain@v1
       with:
-        toolchain: 1.55.0
+        toolchain: 1.56.0
         components: clippy
         override: true
         profile: minimal