WIP: Start preparing release v3.0.7 (#147)

* Use ooni/probe-engine 0.16.0
* Update all the other dependencies
* Use GitHub Actions rather than Travis CI
* Automatically build and test binaries on the target OS (for Windows, macOS, Linux on amd64)
* Make sure we correctly measure coverage
* Make sure we use `-race` when running tests
* Remove unnecessary scripts
* Make sure the README is up-to-date
* Write small script to update binary data and add GitHub Actions checks for it
* Notice that we needed to run ./updatebindata.sh and run it
* Self documenting instructions regarding cross compiling
* Set version number to v3.0.7-beta

Part of https://github.com/ooni/probe-engine/issues/748

.github/workflows/linux.yml

@@ -0,0 +1,20 @@
+# Build and test Linux binary
+name: linux
+on:
+  push:
+  schedule:
+    - cron: "14 17 * * 3"
+jobs:
+  build:
+    runs-on: "ubuntu-latest"
+    steps:
+      - uses: actions/setup-go@v1
+        with:
+          go-version: "1.14"
+      - uses: actions/checkout@v2
+      - run: ./build.sh linux
+      - run: ./smoketest.sh ./CLI/linux/amd64/ooniprobe
+      - uses: actions/upload-artifact@v1
+        with:
+          name: ooniprobe-linux-amd64
+          path: ./CLI/linux/amd64/ooniprobe