chore(deps): switch dependabot package ecosystem from pip to uv

- drop update-uv-lock workflow also

Signed-off-by: jmeridth <jmeridth@gmail.com>

Author: jmeridth

.github/dependabot.yml

@@ -1,7 +1,7 @@
 ---
 version: 2
 updates:
-  - package-ecosystem: "pip" # See documentation for possible values
+  - package-ecosystem: "uv"
     directory: "/" # Location of package manifests
     schedule:
       interval: "weekly"