Add a dependency for lsb_release

We use lsb_release currently in pipeline scripts to determine the Ubuntu
version. Add it as dependency to ensure it's installed everywhere; it's
likely we'll rely on its functionality in more scripts going forward.

Signed-off-by: Philipp Wagner <phw@lowrisc.org>
diff --git a/apt-requirements.txt b/apt-requirements.txt
index 19da59a..2710fb7 100644
--- a/apt-requirements.txt
+++ b/apt-requirements.txt
@@ -18,6 +18,7 @@
 libftdi1-dev
 libssl-dev
 libusb-1.0-0
+lsb-release
 make
 ninja-build
 pkgconf