build: missing regex include. (#8032)
build: missing regex include. (#8032)

Signed-off-by: Harvey Tuch <c185081708e02336640916420d0c772668570de5@google.com>
envoyproxy/envoy,envoyproxy/envoy,lizan/envoy,jrajahalme/envoy,eklitzke/envoy,istio/envoy,eklitzke/envoy,istio/envoy,envoyproxy/envoy-wasm,envoyproxy/envoy,lizan/envoy,istio/envoy,envoyproxy/envoy-wasm,istio/envoy,istio/envoy,lyft/envoy,lizan/envoy,jrajahalme/envoy,lyft/envoy,eklitzke/envoy,envoyproxy/envoy,envoyproxy/envoy,eklitzke/envoy,jrajahalme/envoy,eklitzke/envoy,lizan/envoy,istio/envoy,lyft/envoy,envoyproxy/envoy,lizan/envoy,envoyproxy/envoy,envoyproxy/envoy,envoyproxy/envoy,lizan/envoy,envoyproxy/envoy,envoyproxy/envoy-wasm,lyft/envoy,jrajahalme/envoy,envoyproxy/envoy-wasm,istio/envoy,lyft/envoy,eklitzke/envoy,envoyproxy/envoy,envoyproxy/envoy-wasm,lyft/envoy,envoyproxy/envoy,jrajahalme/envoy,envoyproxy/envoy-wasm,envoyproxy/envoy-wasm,jrajahalme/envoy