Consider making content-type application/json header optional

[mattsse]

Component

Anvil

Describe the feature you would like

geth requires "Content-Type: application/json", while dev nodes like ganache,hh or providers do not.

in anvil this is enforced by axum::Json type which treats missing content-type as an error with no way to opt out.

this could only be resolved by rolling a custom Json wrapper

Additional context

No response