doc: Update DEVELOPMENT.md, PULL_REQUEST_TEMPLATE.md to include usage…

… of new dependency packages

Signed-off-by: David Leong <[email protected]>

.github/PULL_REQUEST_TEMPLATE.md

@@ -20,6 +20,12 @@ See [DEVELOPMENT.md](https://github.com/aws-deadline/deadline-cloud/blob/mainlin
 - Are relevant docstrings in the code base updated?
 - Has the README.md been updated? If you modified CLI arguments, for instance.
 
+### Does this PR introduce new dependencies?
+
+- Does it add new package dependencies to `dependencies` section of `pyproject.toml`? 
+- Please consider why a new dependency is needed? Dependency libraries need to be updated or maintained.
+- Is this dependency small enough to be implemented and added to the `deadline-cloud project`?
+
 ### Is this a breaking change?
 
 A breaking change is one that modifies a public contract in a way that is not backwards compatible. See the 

DEVELOPMENT.md

@@ -201,6 +201,13 @@ For the Python library interface:
 * Changing the location that a file or directory is created should be considered to be a breaking change. These locations have a tendancy to become
   de-facto parts of the public contract as users build automation that assumes these locations is unchanged.
 
+### Library Dependencies
+
+Library dependencies are Python packages required to build and run the Deadline Cloud Python project. Dependencies are specified in the `dependencies` section of `pyproject.toml`.
+
+We try to minimize the number of dependencies required to build and run Deadline Cloud. When contributing changes, please consider the following. Why is a new dependency needed? Is the dependency library functionality required small enough to have a minimal version added to the Deadline Cloud code base?
+
+
 ### Qt and Calling AWS (including AWS Deadline Cloud) APIs
 
 > TL;DR Never call an AWS API from the main Qt event loop. Always run it in a separate thread,