buildman: Create a requirements.txt file

At this point, buildman requires a few different modules and so we need
a requirements.txt to track what modules are needed.

Cc: Simon Glass <sjg@chromium.org>
Cc: Neha Malcom Francis <n-francis@ti.com>
Reviewed-by: Simon Glass <sjg@chromium.org>
Signed-off-by: Neha Malcom Francis <n-francis@ti.com>
Signed-off-by: Tom Rini <trini@konsulko.com>
diff --git a/tools/buildman/requirements.txt b/tools/buildman/requirements.txt
new file mode 100644
index 0000000..a1efcb9
--- /dev/null
+++ b/tools/buildman/requirements.txt
@@ -0,0 +1,2 @@
+jsonschema==4.17.3
+pyyaml==6.0