docs: updating deps doc

Author: samrose

nix/docs/updating-dependencies.md

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+# Updating Dependencies
+
+This document explains how to update various dependencies used in the nix configuration.
+
+## Updating Packer
+
+Packer is used for creating machine images and is defined in `nix/packages/packer.nix`.
+
+### Steps to update Packer version:
+
+1. Create a branch off of `develop`
+2. Navigate to `nix/packages/packer.nix`
+3. Update the version field:
+   ```nix
+   version = "1.15.0"; # Update to desired version
+   ```
+4. Update the git revision to match the new version:
+   ```nix
+   rev = "v${version}";
+   ```
+5. Temporarily clear the hash to get the new SHA256:
+   ```nix
+   hash = ""; # Clear this temporarily
+   ```
+6. Save the file and run:
+   ```bash
+   nix build .#packer
+   ```
+7. Nix will fail and output the correct SHA256 hash. Copy this hash and update the file:
+   ```nix
+   hash = "sha256-NEWHASHHEREFROMBUILDOUTPUT";
+   ```
+8. Update the vendorHash if needed. If the build fails due to vendor hash mismatch, temporarily set:
+   ```nix
+   vendorHash = ""; # Clear this temporarily
+   ```
+9. Run `nix build .#packer` again to get the correct vendorHash, then update:
+   ```nix
+   vendorHash = "sha256-NEWVENDORHASHHEREFROMBUILDOUTPUT";
+   ```
+10. Verify the build works:
+    ```bash
+    nix build .#packer
+    ```
+11. Test the packer binary:
+    ```bash
+    ./result/bin/packer version
+    ```
+12. Run the full test suite to ensure nothing is broken:
+    ```bash
+    nix flake check -L
+    ```
+13. Commit your changes and create a PR for review
+14. Update any CI/CD workflows or documentation that reference the old Packer version
+
+### Notes:
+- Always check the [Packer changelog](https://github.com/hashicorp/packer/releases) for breaking changes
+- Packer uses Go, so ensure compatibility with the Go version specified in the flake inputs
+- The current Go version is specified in `flake.nix` under `nixpkgs-go124` input
+- If updating to a major version, test all packer templates (`.pkr.hcl` files) in the repository
+
+## Updating Other Dependencies
+
+Similar patterns can be followed for other dependencies defined in the nix packages. Always:
+1. Check for breaking changes in changelogs
+2. Update version numbers and hashes
+3. Run local tests
+4. Verify functionality before creating PR