build: configure cross-platform builds with Goreleaser

- Add a new file `.goreleaser.yaml`
- Configure builds for multiple operating systems and architectures
- Set flags and ldflags for the builds
- Add a binary name template for the builds
- Add an archive format
- Add a checksum template
- Add a snapshot template

Signed-off-by: Bo-Yi.Wu <appleboy.tw@gmail.com>

.goreleaser.yaml

@@ -0,0 +1,84 @@
+before:
+  hooks:
+    - go mod tidy
+
+builds:
+- env:
+  - CGO_ENABLED=0
+  goos:
+  - darwin
+  - linux
+  - windows
+  - freebsd
+  goarch:
+  - amd64
+  - arm
+  - arm64
+  goarm:
+  - "5"
+  - "6"
+  - "7"
+  ignore:
+    - goos: darwin
+      goarch: arm
+    - goos: darwin
+      goarch: ppc64le
+    - goos: darwin
+      goarch: s390x
+    - goos: windows
+      goarch: ppc64le
+    - goos: windows
+      goarch: s390x
+    - goos: windows
+      goarch: arm
+      goarm: "5"
+    - goos: windows
+      goarch: arm
+      goarm: "6"
+    - goos: windows
+      goarch: arm
+      goarm: "7"
+    - goos: windows
+      goarch: arm64
+    - goos: freebsd
+      goarch: ppc64le
+    - goos: freebsd
+      goarch: s390x
+    - goos: freebsd
+      goarch: arm
+      goarm: "5"
+    - goos: freebsd
+      goarch: arm
+      goarm: "6"
+    - goos: freebsd
+      goarch: arm
+      goarm: "7"
+    - goos: freebsd
+      goarch: arm64
+  flags:
+  - -trimpath
+  ldflags:
+  - -s -w
+  - -X github.com/appleboy/drone-ssh.Version={{.Version}}
+  binary: >-
+    {{ .ProjectName }}-
+    {{- if .IsSnapshot }}{{ .Branch }}-
+    {{- else }}{{- .Version }}-{{ end }}
+    {{- .Os }}-
+    {{- if eq .Arch "amd64" }}amd64
+    {{- else if eq .Arch "amd64_v1" }}amd64
+    {{- else if eq .Arch "386" }}386
+    {{- else }}{{ .Arch }}{{ end }}
+    {{- if .Arm }}-{{ .Arm }}{{ end }}
+  no_unique_dist_dir: true
+
+archives:
+  - format: binary
+    name_template: "{{ .Binary }}"
+    allow_different_binary_count: true
+
+checksum:
+  name_template: 'checksums.txt'
+
+snapshot:
+  name_template: "{{ incpatch .Version }}"