Migrate CI to github actions

Author: Tibo-lg

.github/workflows/rust.yml

@@ -0,0 +1,62 @@
+on: [push, pull_request]
+
+name: Continuous integration
+
+jobs:
+    tests:
+        name: Tests
+        runs-on: ubuntu-latest
+        strategy:
+            matrix:
+                include:
+                    - rust: stable
+                      env:
+                          RUSTFMTCHK: true
+                    - rust: nightly
+                      env:
+                          RUSTFMTCHK: false
+                    - rust: 1.29.0
+                      env:
+                          PIN_VERSIONS: true
+        steps:
+            - name: Checkout Crate
+              uses: actions/checkout@v2
+            - name: Checkout Toolchain
+              uses: actions-rs/toolchain@v1
+              with:
+                  profile: minimal
+                  toolchain: ${{ matrix.rust }}
+                  override: true
+            - name: Running test script
+              env: ${{ matrix.env }}
+              run: ./contrib/test.sh
+
+    integrations-tests:
+        name: Integration Tests
+        runs-on: ubuntu-latest
+        strategy:
+            matrix:
+                rust: [stable]
+                bitcoinversion:
+                    [
+                        "0.18.0",
+                        "0.18.1",
+                        "0.19.0.1",
+                        "0.19.1",
+                        "0.20.0",
+                        "0.20.1",
+                        "0.21.0",
+                    ]
+        steps:
+            - name: Checkout Crate
+              uses: actions/checkout@v2
+            - name: Checkout Toolchain
+              uses: actions-rs/toolchain@v1
+              with:
+                  profile: minimal
+                  toolchain: ${{ matrix.rust }}
+                  override: true
+            - name: Running test script
+              env:
+                  BITCOINVERSION: ${{ matrix.bitcoinversion }}
+              run: ./contrib/test.sh

.travis.yml

@@ -2,14 +2,13 @@
 set -xe
 
 # Just echo all the relevant env vars to help debug Travis.
-echo "TRAVIS_RUST_VERSION: \"$TRAVIS_RUST_VERSION\""
 echo "RUSTFMTCHECK: \"$RUSTFMTCHECK\""
 echo "BITCOINVERSION: \"$BITCOINVERSION\""
 echo "PATH: \"$PATH\""
 
 
 # Pin dependencies for Rust v1.29
-if [ "$TRAVIS_RUST_VERSION" = "1.29.0" ]; then
+if [ -n $"$PIN_VERSIONS" ]; then
     cargo generate-lockfile --verbose
 
     cargo update --verbose --package "log" --precise "0.4.13"
@@ -34,9 +33,10 @@ if [ -n "$BITCOINVERSION" ]; then
     cd integration_test
     ./run.sh
     exit 0
+else
+  # Regular build/unit test.
+  cargo build --verbose
+  cargo test --verbose
+  cargo build --verbose --examples
 fi
 
-# Regular build/unit test.
-cargo build --verbose
-cargo test --verbose
-cargo build --verbose --examples