Update changelogs

Signed-off-by: Jorge Turrado <jorge.turrado@mail.schwarz>

Author: JorTurFer

CHANGELOG.md

@@ -1,4 +1,7 @@
 ## Release (2025-XX-YY)
+- `core`: 
+  - [v0.21.0](core/CHANGELOG.md#v0210)
+    - **Chore:** Use `jwt-bearer` grant to get a fresh token instead of `refresh_token`
 - `scf`: [v0.3.0](services/scf/CHANGELOG.md#v030)
   - **Feature:** Add new model `IsolationSegment` and `IsolationSegmentsList`
 - `iaas`: 

core/CHANGELOG.md

@@ -1,3 +1,6 @@
+## v0.21.0
+- **Chore:** Use `jwt-bearer` grant to get a fresh token instead of `refresh_token`
+
 ## v0.20.1
 - **Improvement:** Improve error message when passing a PEM encoded file to as service account key
 
@@ -9,6 +12,7 @@
 
 ## v0.18.0
 - **New:** Added duration utils
+- **Chore:** Use `jwt-bearer` grant to get a fresh token instead of `refresh_token`
 
 ## v0.17.3 
 - **Dependencies:** Bump `github.com/golang-jwt/jwt/v5` from `v5.2.2` to `v5.2.3`

core/VERSION

@@ -1 +1 @@
-v0.20.1
+v0.21.0