Bump minor version of lambda_http in pokemon-service

This commit updates the version of `lambda_http` used by `pokemon-service`
from 0.6.0 to 0.7.0. This is in sync with the fact that both
`aws-smithy-http-server` and `aws-smithy-http-server-python` now depend
on 0.7.0 of `lambda_http`. Failing to do so would cause `pokemon-service`
to fail to compile due to an error at `lambda_http::run(handler)` in the
main function of the `pokemon-service-lambda` binary:
the trait `Service<lambda_http::http::Request<lambda_http::Body>>` is not
implemented for `LambdaHandler<aws_smithy_http_server::routing::Router>`

rust-runtime/aws-smithy-http-server/examples/pokemon-service/Cargo.toml

@@ -37,7 +37,7 @@ rustls-pemfile = "1.0.1"
 futures-util = "0.3"
 
 # This dependency is only required for the `pokemon-service-lambda` program.
-lambda_http = "0.6.0"
+lambda_http = "0.7.0"
 
 # Local paths
 aws-smithy-http-server = { path = "../../" }