ci: Windows: Add gperf to dependency list

msys2 removed the gperf package from the base-devel package collection[1].

Add gperf explicitly to the dependency list, without this the Windows
CI will fail.

[1] msys2/MSYS2-packages@085698d

Signed-off-by: Lars-Peter Clausen <lars@metafoo.de>

.github/workflows/test.yml

@@ -99,6 +99,7 @@ jobs:
         install: >
           git
           base-devel
+          gperf
           mingw-w64-${{ matrix.arch }}-toolchain
 
     - name: Build and check