ci: add configration for gem deployment

.travis.yml

@@ -1,7 +1,7 @@
 language: ruby
 cache: bundler
 rvm:
-  - &latest_ruby 2.7
+- 2.7
 - 2.3
 env:
   global:
@@ -10,9 +10,9 @@ env:
   - JEKYLL_VERSION="~> 3.8"
 matrix:
   include:
-    - rvm: *latest_ruby
+  - rvm: 2.7
     env: JEKYLL_VERSION="~> 3.8.6"
-    - rvm: *latest_ruby
+  - rvm: 2.7
     env: JEKYLL_VERSION=">= 4.0.0"
 before_install:
 - gem update --system
@@ -21,3 +21,12 @@ before_script: bundle update
 script: script/cibuild
 notifications:
   email: false
+deploy:
+  provider: rubygems
+  api_key:
+    secure: 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
+  gem: jekyll-spaceship
+  on:
+    tags: true
+    repo: jeffreytse/jekyll-spaceship
+  cleanup: false