Replace defunct travis ci with github actions

The workflow definition is adapted from gocryptfs,
that uses github actions for a month now.

Works ok as seen here:
https://github.com/rfjakob/go-fuse/actions/runs/1167431646

(except that some tests are flakey, but that's a
problem for another day).

Change-Id: Ib7aaa3b0a2f9671040fa599735aa47323d5c25d4

.github/workflows/ci.yml

+name: CI
+
+on:
+  push:
+  pull_request:
+  schedule:
+    - cron:  '0 12 * * *' # Every day noon UTC
+
+jobs:
+  build:
+    strategy:
+      matrix:
+        go:
+          - "1.13.x" # Ubuntu 20.04 LTS "focal"
+          - "1.15.x" # Debian 11 "Bullseye"
+          - "1.16.x" # Golang upstream stable
+          - "1.17.x" # Golang upstream stable
+      # Don't cancel everything when one Go version fails
+      fail-fast: false
+    runs-on: ubuntu-latest
+    steps:
+
+    - name: Install Go ${{ matrix.go }}
+      uses: actions/setup-go@v2
+      with:
+        go-version: ${{ matrix.go }}
+
+    - uses: actions/checkout@v2
+      with:
+        fetch-depth: 0 # Make "git describe" work
+
+    # CI platform specific setup steps happen here
+    - run: sudo apt-get install -qq fuse3 libssl-dev libfuse-dev
+
+    # Actual test steps are in all.bash
+    - run: ./all.bash

.travis.yml

-sudo: required
-# Ubuntu 18.04 "Bionic", https://docs.travis-ci.com/user/reference/bionic/
-# Kernel 5.0.0-1026-gcp
-dist: bionic
-
-language: go
-go_import_path: github.com/hanwen/go-fuse
-
-go:
-  - 1.10.x
-  - 1.11.x
-  - 1.12.x
-  - 1.13.x
-  - 1.14.x
-  - 1.15.x
-  - master
-
-env:
-  - GOMAXPROCS=1
-  # vvv = native `nproc`
-  - GOMAXPROCS=
-
-matrix:
- fast_finish: true
- allow_failures:
-   - go: master
-
-before_install:
-  - sudo apt-get install -qq pkg-config fuse
-  - sudo modprobe fuse
-  - sudo chmod 666 /dev/fuse
-  - sudo chown root:$USER /etc/fuse.conf
-
-install:
-  - go get -t ./...
-  - go get -t -race ./...
-
-# Travis CI has a no-output-timeout of 10 minutes.
-# Set "go test -timeout" lower so we get proper backtraces
-# on a hung test.
-# The tests sometimes hang in a way that "go test -timeout"
-# does not work anymore. Use the external "timeout" command
-# as backup, triggering 1 minute later.
-script:
-  - set -e # fail fast
-  - timeout -s QUIT -k 10s 90s go test -failfast -timeout 1m -p 1 -v ./fs
-  - timeout -s QUIT -k 10s 6m  go test -failfast -timeout 5m -p 1 -v ./...
-  - set +e # restore

README.md

 # GO-FUSE
 
-[![Build Status](https://travis-ci.org/hanwen/go-fuse.svg?branch=master)](https://travis-ci.org/hanwen/go-fuse)
+[![CI](https://github.com/hanwen/go-fuse/actions/workflows/ci.yml/badge.svg)](https://github.com/hanwen/go-fuse/actions/workflows/ci.yml)
 [![GoDoc](https://godoc.org/github.com/hanwen/go-fuse?status.svg)](https://godoc.org/github.com/hanwen/go-fuse)
 
 Go native bindings for the FUSE kernel module.