Replace Travis CI badge to GitHub Actions
Replace Travis CI badge to GitHub Actions

Signed-off-by: Takuya Noguchi <b6ff22f4ae6fe3ca1371a0ef8d104f1c4bca551b@gmail.com>

KnapsackPro/docs.knapsackpro.com,KnapsackPro/docs.knapsackpro.com,KnapsackPro/docs.knapsackpro.com