MT#64553 debian/changelog: refresh version

As the current branch version in trunk is mr26.1.0, update the current
version to stay within this release. Otherwise, the night tests will
continue to fail as the current asterisk version (mr26.2.0) is higher
than the expected version of trunk (mr26.1.0).

```
02:12:58 Expected NGCP version mr26.1.0 (detected from ngcp-ngcp-ce)
02:12:58 ii  ngcp-asterisk-voicemail-odbcstorage                      22.8.2+0~mr26.2.0.0+0~20260420141757.1452+trixie~1.gbpa5e8d2     amd64        NGCP version ODBC voicemail storage support for the Asterisk PBX
02:12:58 ERROR: 1 package(s) with wrong version, see above!
02:12:58 Build step 'Execute shell' marked build as failure
```

Note: Thanks to @mprokop, some actions on the repository were executed
in order to allow reprepro to do this downgrade. See comments.

Change-Id: Ifdb8777d95c5cb373d2740589e0015b224ea16bd

debian/changelog

@@ -1,4 +1,4 @@
-ngcp-asterisk-voicemail (22.8.2+0~mr26.2.0.0) unstable; urgency=medium
+ngcp-asterisk-voicemail (22.8.2+0~mr26.1.0.1) unstable; urgency=medium
 
   [ Donat Zenichev ]
   * [6363bc9] MT#64553 support trixie 22.8.2+dfsg+~cs6.15.60671435-1~bpo13+1