Use bellatrix in upgrade_x_to_capella helpers

specs/capella/light-client/fork.md

@@ -22,14 +22,14 @@ This document describes how to upgrade existing light client objects based on th
 A Capella `LightClientStore` can still process earlier light client data. In order to do so, that pre-Capella data needs to be locally upgraded to Capella before processing.
 
 ```python
-def upgrade_lc_header_to_capella(pre: altair.LightClientHeader) -> LightClientHeader:
+def upgrade_lc_header_to_capella(pre: bellatrix.LightClientHeader) -> LightClientHeader:
     return LightClientHeader(
         beacon=pre.beacon,
     )
 ```
 
 ```python
-def upgrade_lc_bootstrap_to_capella(pre: altair.LightClientBootstrap) -> LightClientBootstrap:
+def upgrade_lc_bootstrap_to_capella(pre: bellatrix.LightClientBootstrap) -> LightClientBootstrap:
     return LightClientBootstrap(
         header=upgrade_lc_header_to_capella(pre.header),
         current_sync_committee=pre.current_sync_committee,
@@ -38,7 +38,7 @@ def upgrade_lc_bootstrap_to_capella(pre: altair.LightClientBootstrap) -> LightCl
 ```
 
 ```python
-def upgrade_lc_update_to_capella(pre: altair.LightClientUpdate) -> LightClientUpdate:
+def upgrade_lc_update_to_capella(pre: bellatrix.LightClientUpdate) -> LightClientUpdate:
     return LightClientUpdate(
         attested_header=upgrade_lc_header_to_capella(pre.attested_header),
         next_sync_committee=pre.next_sync_committee,
@@ -51,7 +51,7 @@ def upgrade_lc_update_to_capella(pre: altair.LightClientUpdate) -> LightClientUp
 ```
 
 ```python
-def upgrade_lc_finality_update_to_capella(pre: altair.LightClientFinalityUpdate) -> LightClientFinalityUpdate:
+def upgrade_lc_finality_update_to_capella(pre: bellatrix.LightClientFinalityUpdate) -> LightClientFinalityUpdate:
     return LightClientFinalityUpdate(
         attested_header=upgrade_lc_header_to_capella(pre.attested_header),
         finalized_header=upgrade_lc_header_to_capella(pre.finalized_header),
@@ -62,7 +62,7 @@ def upgrade_lc_finality_update_to_capella(pre: altair.LightClientFinalityUpdate)
 ```
 
 ```python
-def upgrade_lc_optimistic_update_to_capella(pre: altair.LightClientOptimisticUpdate) -> LightClientOptimisticUpdate:
+def upgrade_lc_optimistic_update_to_capella(pre: bellatrix.LightClientOptimisticUpdate) -> LightClientOptimisticUpdate:
     return LightClientOptimisticUpdate(
         attested_header=upgrade_lc_header_to_capella(pre.attested_header),
         sync_aggregate=pre.sync_aggregate,
@@ -75,7 +75,7 @@ def upgrade_lc_optimistic_update_to_capella(pre: altair.LightClientOptimisticUpd
 Existing `LightClientStore` objects based on Altair MUST be upgraded to Capella before Capella based light client data can be processed. The `LightClientStore` upgrade MAY be performed before `CAPELLA_FORK_EPOCH`.
 
 ```python
-def upgrade_lc_store_to_capella(pre: altair.LightClientStore) -> LightClientStore:
+def upgrade_lc_store_to_capella(pre: bellatrix.LightClientStore) -> LightClientStore:
     if pre.best_valid_update is None:
         best_valid_update = None
     else: