Add missing make dist entry
diff --git a/lib/py/Makefile.am b/lib/py/Makefile.am
index a075eb1..78bce7c 100644
--- a/lib/py/Makefile.am
+++ b/lib/py/Makefile.am
@@ -54,6 +54,7 @@
 	CMakeLists.txt \
 	coding_standards.md \
 	compat \
+	requirements.txt \
 	setup.py \
 	setup.cfg \
 	src \