Increase constraint (#1876)

## Problem

ppc fails to build due to run out of space


## Solution

increase disk constrain to ensure there is enough space. Probably caused
by that new xtask compilation task that eats another space.


## Testing

Testing in my IBS branch
https://build.suse.de/package/show/home:jreidinger:branches:Devel:YaST:Agama:Head/agama

rust/package/_constraints

@@ -2,7 +2,7 @@
   <hardware>
     <jobs>4</jobs>
     <disk>
-      <size unit="G">20</size>
+      <size unit="G">25</size>
     </disk>
     <physicalmemory>
       <size unit="G">8</size>

rust/package/agama.changes

@@ -1,3 +1,9 @@
+-------------------------------------------------------------------
+Thu Jan  9 12:52:05 UTC 2025 - Josef Reidinger <[email protected]>
+
+- Increase disk size in _constraints to fix build on ppc
+  (gh#agama-project/agama#1876).
+
 -------------------------------------------------------------------
 Wed Jan  8 14:05:34 UTC 2025 - Imobach Gonzalez Sosa <[email protected]>