ci: downgrade Ledger sim builder to Ubuntu 22.04

On Ubuntu-latest the Speculos sim fails to build:

```
In file included from /home/runner/work/HWI/HWI/test/work/speculos/src/bolos/io/io.c:11:
/home/runner/work/HWI/HWI/test/work/speculos/src/bolos/io/mock/include/os_utils.h:17:22: error: static declaration of ‘strlcpy’ follows non-static declaration
   17 | static inline size_t strlcpy(char *dst, const char *src, size_t size)
      |                      ^~~~~~~
In file included from /home/runner/work/HWI/HWI/test/work/speculos/src/bolos/cx_hash.h:4,
                 from /home/runner/work/HWI/HWI/test/work/speculos/src/bolos/cx.h:11,
                 from /home/runner/work/HWI/HWI/test/work/speculos/src/emulate.h:15,
                 from /home/runner/work/HWI/HWI/test/work/speculos/src/bolos/io/io.c:10:
/usr/arm-linux-gnueabihf/include/string.h:506:15: note: previous declaration of ‘strlcpy’ with type ‘size_t(char * restrict,  const char * restrict,  size_t)’ {aka ‘unsigned int(char * restrict,  const char * restrict,  unsigned int)’}
  506 | extern size_t strlcpy (char *__restrict __dest,
      |               ^~~~~~~
make[2]: *** [src/CMakeFiles/emu.dir/build.make:737: src/CMakeFiles/emu.dir/bolos/io/io.c.o] Error 1
make[2]: Leaving directory '/home/runner/work/HWI/HWI/test/work/speculos/build'
make[1]: *** [CMakeFiles/Makefile2:1285: src/CMakeFiles/emu.dir/all] Error 2
make[1]: Leaving directory '/home/runner/work/HWI/HWI/test/work/speculos/build'
make: *** [Makefile:101: all] Error 2
make: Leaving directory '/home/runner/work/HWI/HWI/test/work/speculos/build'
```

See e.g. https://github.com/bitcoin-core/HWI/actions/runs/16463666304/job/46535976240

Author: Sjors

.github/workflows/ci.yml

@@ -202,7 +202,7 @@ jobs:
 
   sim-builder-ledger:
     name: Ledger sim builder
-    runs-on: ubuntu-latest
+    runs-on: ubuntu-22.04
 
     strategy:
       fail-fast: false