Chore: replace travis CI with GitHub workflows

.github/workflows/audit.yml

@@ -0,0 +1,26 @@
+name: Security audit
+
+on:
+  pull_request:
+    branches:
+      - develop
+    paths:
+      - '**/Cargo.toml'
+      - '**/Cargo.lock'
+
+permissions:
+  contents: read
+
+jobs:
+  security_audit:
+    runs-on: ubuntu-latest
+    steps:
+      - uses: actions/checkout@v3
+      - uses: actions-rs/toolchain@v1
+        with:
+          profile: minimal
+          toolchain: stable
+      - uses: Swatinem/rust-cache@v1
+      - uses: actions-rs/audit-check@v1
+        with:
+          token: ${{ secrets.GITHUB_TOKEN }}

.github/workflows/rust.yml

@@ -0,0 +1,38 @@
+name: Rust compile & test
+
+on:
+  push:
+    branches:
+      - develop
+  pull_request:
+    branches:
+      - develop
+
+permissions:
+  contents: read
+
+jobs:
+  build:
+    runs-on: ubuntu-latest
+    steps:
+    - uses: actions/checkout@v3
+    - name: Install minimal stable with clippy and rustfmt
+      uses: actions-rs/toolchain@v1
+      with:
+        profile: minimal
+        toolchain: stable
+    - uses: Swatinem/rust-cache@v1
+    - name: Run cargo check
+      uses: actions-rs/cargo@v1
+      with:
+        command: check
+    - name: Run build
+      uses: actions-rs/cargo@v1
+      with:
+        command: build
+        args: --verbose
+    - name: Run tests
+      uses: actions-rs/cargo@v1
+      with:
+        command: test
+        args: --verbose

README.asciidoc

@@ -1,7 +1,5 @@
 # Wire
 
-image:https://travis-ci.org/wireapp/proteus.svg?branch=develop["Build Status", link="https://travis-ci.org/wireapp/proteus"]
-
 This repository is part of the source code of Wire. You can find more information at https://wire.com[wire.com] or by contacting opensource@wire.com.
 
 You can find the published source code at https://github.com/wireapp[github.com/wireapp].