add github actions to dependabot config (#3633)
add github actions to dependabot config (#3633)

Co-authored-by: Richard North <39063181cb36256cba7d1d358fd239e3b24c2640@gmail.com>
rnorth/test-containers,rnorth/test-containers,testcontainers/testcontainers-java,rnorth/test-containers,testcontainers/testcontainers-java,testcontainers/testcontainers-java