fix(pbs): increase get header response size (#320)

Author: ltitanb

crates/pbs/src/constants.rs

@@ -15,7 +15,7 @@ pub const MAX_SIZE_SUBMIT_BLOCK_RESPONSE: usize = 20 * 1024 * 1024;
 /// 20 MiB, enough to process ~45000 registrations in one request
 pub const MAX_SIZE_REGISTER_VALIDATOR_REQUEST: usize = 20 * 1024 * 1024;
 
-/// 10 KiB, headers are around 700 bytes + buffer for encoding
-pub const MAX_SIZE_GET_HEADER_RESPONSE: usize = 10 * 1024;
+/// 5 MiB, to account for max execution requests / commitments
+pub const MAX_SIZE_GET_HEADER_RESPONSE: usize = 5 * 1024 * 1024;
 
 pub const MAX_SIZE_DEFAULT: usize = 1024;