Update MSRV to 1.57

Author: jturner314

.github/workflows/ci.yml

@@ -0,0 +1,79 @@
+on:
+  push:
+    branches: [ master ]
+  pull_request:
+    branches: [ master ]
+
+name: Continuous integration
+
+env:
+  CARGO_TERM_COLOR: always
+  HOST: x86_64-unknown-linux-gnu
+  FEATURES: "test docs"
+  RUSTFLAGS: "-D warnings"
+
+jobs:
+  tests:
+    runs-on: ubuntu-latest
+    strategy:
+      matrix:
+        rust:
+          - stable
+          - beta
+          - nightly
+          - 1.57.0  # MSRV
+
+    steps:
+      - uses: actions/checkout@v2
+      - uses: actions-rs/toolchain@v1
+        with:
+          profile: minimal
+          toolchain: ${{ matrix.rust }}
+          override: true
+      - name: Install openblas
+        run: sudo apt-get install libopenblas-dev gfortran
+      - run: ./scripts/all-tests.sh "$FEATURES" ${{ matrix.rust }}
+
+  cross_test:
+    runs-on: ubuntu-latest
+    strategy:
+      matrix:
+        include:
+          - rust: stable
+            target: mips-unknown-linux-gnu
+          - rust: stable
+            target: i686-unknown-linux-gnu
+
+    steps:
+      - uses: actions/checkout@v2
+      - uses: actions-rs/toolchain@v1
+        with:
+          profile: minimal
+          toolchain: ${{ matrix.rust }}
+          target: ${{ matrix.target }}
+          override: true
+      - name: Cache cargo plugins
+        uses: actions/cache@v1
+        with:
+          path: ~/.cargo/bin/
+          key: ${{ runner.os }}-cargo-plugins
+      - name: Install cross
+        run: cargo install cross || true
+      - run: ./scripts/cross-tests.sh "docs" ${{ matrix.rust }} ${{ matrix.target }}
+
+  clippy:
+    runs-on: ubuntu-latest
+    strategy:
+      matrix:
+        rust:
+          - beta
+    steps:
+      - uses: actions/checkout@v2
+      - uses: actions-rs/toolchain@v1
+        with:
+          profile: minimal
+          toolchain: ${{ matrix.rust }}
+          override: true
+          components: clippy
+      - run: cargo clippy --features docs
+

Cargo.toml

@@ -3,7 +3,7 @@
 name = "ndarray"
 version = "0.15.6"
 edition = "2018"
-rust-version = "1.51"
+rust-version = "1.57"
 authors = [
   "Ulrik Sverdrup \"bluss\"",
   "Jim Turner"