bazel: update rules_kotlin shallow_since (#183)
bazel: update rules_kotlin shallow_since (#183)

Resolves the following warning when building:

> DEBUG: Rule 'io_bazel_rules_kotlin' indicated that a canonical reproducible form can be obtained by modifying arguments shallow_since = "1556831609 -0700"

Signed-off-by: Michael Rebello <d207f8179edebd36c6ff33f7db1973b360eda8cd@lyft.com>
envoyproxy/envoy-mobile,envoyproxy/envoy-mobile,envoyproxy/envoy-mobile,envoyproxy/envoy-mobile,envoyproxy/envoy-mobile,envoyproxy/envoy-mobile,envoyproxy/envoy-mobile,envoyproxy/envoy-mobile,envoyproxy/envoy-mobile