Add requirements file and its pip-compile template

requirements.in

@@ -0,0 +1,3 @@
+requests
+lxml
+rich

requirements.txt

@@ -0,0 +1,26 @@
+#
+# This file is autogenerated by pip-compile with python 3.10
+# To update, run:
+#
+#    pip-compile
+#
+certifi==2021.10.8
+    # via requests
+charset-normalizer==2.0.12
+    # via requests
+colorama==0.4.4
+    # via rich
+commonmark==0.9.1
+    # via rich
+idna==3.3
+    # via requests
+lxml==4.8.0
+    # via -r requirements.in
+pygments==2.11.2
+    # via rich
+requests==2.27.1
+    # via -r requirements.in
+rich==11.2.0
+    # via -r requirements.in
+urllib3==1.26.8
+    # via requests