add ADR 0006: Use for dependency management

docs/adrs/0006-use-for-dependency-management.md

@@ -0,0 +1,36 @@
+# Use  for dependency management
+
+Date: 2023-09-08
+
+### Status
+
+Accepted
+
+### Context
+
+Our initial decision to use  was primarily driven by [built-in support in Cloud Foundry](https://docs.cloudfoundry.org/buildpacks/python/index.html#pipenv). In practice, we have found that we still need to export the requirements file as part of the build process, removing the benefit.
+
+Meanwhile,  appears to be the informal standard around TTS. It's relatively simple for a dev to switch between them, but we do value consistency across the organization.
+
+### Decision
+
+Let's use .
+
+### Consequences
+
+We expect this to be a one-time cost.
+
+### Author
+
+@stvnrlly
+
+
+### Next Steps
+
+We will need to:
+
+- Convert to 
+- Convert our CI/CD processes
+- Ensure [proper Dependabot configuration](https://docs.github.com/en/code-security/dependabot/dependabot-version-updates/configuration-options-for-the-dependabot.yml-file)
+- Update developer documentation
+- Get familiar with the tool