test: Using since in custom template

See https://github.com/appleboy/drone-telegram/issues/89

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

pipeline.libsonnet

@@ -237,7 +237,7 @@
         settings: {
           to: { from_secret: 'telegram_to' },
           token: { from_secret: 'telegram_token' },
-          message: '{{#success build.status}} ✅  Build #{{build.number}} of `{{repo.name}}` succeeded.\n\n📝 Commit by {{commit.author}} on `{{commit.branch}}`:\n``` {{commit.message}} ```\n\n🌐 {{ build.link }} {{else}} ❌  Build #{{build.number}} of `{{repo.name}}` failed.\n\n📝 Commit by {{commit.author}} on `{{commit.branch}}`:\n``` {{commit.message}} ```\n\n🌐 {{ build.link }} {{/success}}\n',
+          message: '{{#success build.status}} ✅  Build #{{build.number}} of `{{repo.name}}` succeeded.\n\n📝 Commit by {{commit.author}} on `{{commit.branch}}`:\n``` {{commit.message}} ```\n\n🌐 {{ build.link }} {{else}} ❌  Build #{{build.number}} of `{{repo.name}}` failed.\n\n📝 Commit by {{commit.author}} on `{{commit.branch}}`:\n``` {{commit.message}} ```\n\n🌐 {{ build.link }} {{/success}}\n\n timecost: {{since build.started}}\n',
         },
       },
       {