linux.headers: Update version from 4.14.87 to 5.15.5

Update linux-headers to latest stable version.

I don't expect any problems if linux-headers is newer than the running
kernel. The consumers (mainly glibc) adapts to the running kernel
anyway.

However, if we compile consumers with old headers, we wouldn't be able
to use new kernel features even when we update the kernel.

linux-headers.be0

@@ -1,6 +1,6 @@
 #!/usr/bin/env beesh
 
-# BEE_VERSION linux-headers-4.14.87-0
+# BEE_VERSION linux-headers-5.15.5-0
 
 ## this file was created by bee init and should be executed to build a
 ## bee-package. (Additional hints are located at the end of this file.)