using _ instead of - now

hal/src/fsfw_hal/linux/gpio/CMakeLists.txt

@@ -0,0 +1,12 @@
+target_sources(${LIB_FSFW_NAME} PRIVATE
+    LinuxLibgpioIF.cpp
+)
+
+# This abstraction layer requires the gpiod library. You can install this library
+# with "sudo apt-get install -y libgpiod-dev". If you are cross-compiling, you need
+# to install the package before syncing the sysroot to your host computer.
+find_library(LIB_GPIO gpiod REQUIRED)
+
+target_link_libraries(${LIB_FSFW_NAME} PRIVATE
+    ${LIB_GPIO}
+)