Bump yaml-cpp so it builds with Visual Studio 15.8 (#4182)
Bump yaml-cpp so it builds with Visual Studio 15.8 (#4182)

Version 0.6.2 of yaml-cpp does not build when using Visual Studio 15.8,
for context see: jbeder/yaml-cpp#597

Updating to this commit fixes the issue.

Risk Level:
Low

Testing:
bazel test //test/... on Linux.

Signed-off-by: Sam Smith <03a07629efb0a02c7bbe7cc340a4243da1ab861a@gmail.com>

dnoe/envoy,istio/envoy,lizan/envoy,istio/envoy,dnoe/envoy,istio/envoy,lizan/envoy,envoyproxy/envoy,dnoe/envoy,envoyproxy/envoy-wasm,envoyproxy/envoy,eklitzke/envoy,envoyproxy/envoy,dnoe/envoy,envoyproxy/envoy-wasm,envoyproxy/envoy-wasm,envoyproxy/envoy-wasm,lizan/envoy,envoyproxy/envoy,dnoe/envoy,istio/envoy,eklitzke/envoy,lizan/envoy,envoyproxy/envoy,envoyproxy/envoy,envoyproxy/envoy,eklitzke/envoy,envoyproxy/envoy,envoyproxy/envoy,envoyproxy/envoy,jrajahalme/envoy,lizan/envoy,lyft/envoy,envoyproxy/envoy-wasm,istio/envoy,jrajahalme/envoy,jrajahalme/envoy,lyft/envoy,envoyproxy/envoy,istio/envoy,jrajahalme/envoy,istio/envoy,lizan/envoy,envoyproxy/envoy-wasm,eklitzke/envoy,envoyproxy/envoy-wasm,lyft/envoy,jrajahalme/envoy,lyft/envoy,lyft/envoy,lyft/envoy,envoyproxy/envoy,jrajahalme/envoy,eklitzke/envoy,eklitzke/envoy