feat: switch to Etherscan v2 API

- only `ETHERSCAN_API_KEY` is required now
- switch client from `requests` to `httpx` (HTTP 2, typed, more easily extensible)
- add disk cache to HTTP client
- add etherscan rate limiting on HTTP client
- improve client interface to not require `RootModel` anymore

pyproject.toml

@@ -21,7 +21,6 @@ classifiers = [
 dependencies = [
     "pydantic>=2.8.2",
     "eip712-clearsign>=3.0.1",
-    "requests>=2.32.3",
     "typer>=0.12.5",
     "eth-utils>=5.0.0",
     "jsonschema",
@@ -30,6 +29,11 @@ dependencies = [
     "typer",
     "lark>=1.2.2",
     "pydantic-string-url>=1.0.2",
+    "httpx>=0.27.2",
+    "httpx-file>=0.2.0",
+    "hishel>=0.0.33",
+    "xdg-base-dirs>=6.0.2",
+    "limiter>=0.5.0",
 ]
 
 [project.urls]