added csst_common to requirements for readthedocs

doc/requirements.txt

+numpy==1.23.3
+scipy==1.9.1
+joblib==1.2.0
+setuptools==58.0.4
+astropy==5.1
+pycodestyle==2.9.1
+sphinx_copybutton==0.5.0
+git+https://csst-tb.bao.ac.cn/code/csst-l1/csst_common.git
\ No newline at end of file

readthedocs.yml

@@ -19,7 +19,7 @@ formats:
 python:
   version: 3.8
   install:
-    - requirements: requirements.txt
+    - requirements: doc/requirements.txt
     - method: pip
       path: .