Avoid using locked dependencies in renv.lock when deploying

* This is not working if we are using non-renv CI-CD, and is also not ideal since our `renv.lock` is meant to contain also development dependencies, whereas we would ideally want to have run-time dependencies only.
* Note that `rsconnect::deployApp()` would still use renv internally to creat a snapshot based on what is installed.

.rscignore

@@ -0,0 +1 @@
+renv.lock