chore: bump version for release

Amp-Thread-ID: https://ampcode.com/threads/T-019db2c6-6026-73a8-a772-01da7898bf87
Co-authored-by: Amp <amp@ampcode.com>

Author: alDuncanson

pyproject.toml

@@ -1,6 +1,6 @@
 [project]
 name = "a2a-handler"
-version = "0.1.19"
+version = "0.1.20"
 description = "An A2A Protocol client TUI and CLI."
 readme = "README.md"
 requires-python = ">=3.11"