Add changelogs

Author: jasagredo

ouroboros-consensus-cardano/changelog.d/20250602_165324_jasataco_newer_ledger.md

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+<!--
+A new scriv changelog fragment.
+
+Uncomment the section that is right (remove the HTML comment wrapper).
+For top level release notes, leave all the headers commented out.
+-->
+
+<!--
+### Patch
+
+- A bullet item for the Patch category.
+
+-->
+### Non-Breaking
+
+- Vendor Ledger's serialization of `PParams` and `ShelleyGenesis` prior to `ShelleyNodeToClientVersion12`.
+
+### Breaking
+
+- Define new Node-To-Client versions `CardanoNodeToClientVersion17`, `ShelleyNodeToClientVersion13`.

ouroboros-consensus/changelog.d/20250602_165308_jasataco_newer_ledger.md

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+<!--
+A new scriv changelog fragment.
+
+Uncomment the section that is right (remove the HTML comment wrapper).
+For top level release notes, leave all the headers commented out.
+-->
+
+### Patch
+
+- Fix serialization of `TriggerHardForkNotDuringThisExecution`.
+
+<!--
+### Non-Breaking
+
+- A bullet item for the Non-Breaking category.
+
+-->
+<!--
+### Breaking
+
+- A bullet item for the Breaking category.
+
+-->