fix requirements

requirements.in

@@ -39,3 +39,6 @@ et_xmlfile==1.1.0 # pandas dependency
 
 # manual dependency
 marshmallow-enum==1.4.1
+
+# flask_mail dependency
+blinker==1.5

requirements.txt

@@ -1,8 +1,8 @@
 #
-# This file is autogenerated by pip-compile with python 3.8
+# This file is autogenerated by pip-compile with python 3.9
 # To update, run:
 #
-#    pip-compile --output-file=requirements.txt requirements.in
+#    pip-compile
 #
 alembic==1.4.2
     # via -r requirements.in
@@ -12,6 +12,8 @@ apispec==0.39.0
     # via teal
 atomicwrites==1.4.0
     # via -r requirements.in
+blinker==1.5
+    # via -r requirements.in
 boltons==18.0.1
     # via
     #   ereuse-utils