script: Exclude .cmake for format-cmake.sh

It can help to fix the following error when running format-cmake.sh:
IsADirectoryError: [Errno 21] Is a directory: 'src/xrt/targets/openxr_android/.cxx/Debug/***/arm64-v8a/.cmake'

Signed-off-by: utzcoz <utzcoz@outlook.com>

scripts/format-cmake.sh

@@ -25,6 +25,7 @@ fi
         src/CMakeLists.txt \
         tests \
         \( -name "CMakeLists.txt" -o -name "*.cmake" \) \
+        ! -name ".cmake" \
         -print0 | \
         xargs -0 "${CMAKE_FORMAT}" -c "$(pwd)/.cmake-format.py" -i
 )