Fix problem seen where flatterer 0.18.0 does not exist any more.

(We don't understand why as there is no yanked message. we have contacted author to ask)
To make a minimal change, upgrade to latest 0.18.X only.
Extra packages: We aren't sure why pip-compile added these extra packages.

Author: kathryn-ods

requirements.txt

@@ -41,7 +41,7 @@ docutils==0.17.1
     #   sphinxcontrib-opendataservices-jsonschema
 erd-from-json-table-schema==0.2.0
     # via -r requirements.in
-flatterer==0.18.0
+flatterer==0.18.2
     # via hsds-schema-tools
 fqdn==1.5.1
     # via jsonschema
@@ -55,6 +55,8 @@ ijson==3.2.0.post0
     # via flatterer
 imagesize==1.4.1
     # via sphinx
+importlib-metadata==8.5.0
+    # via sphinx
 isoduration==20.11.0
     # via jsonschema
 jinja2==3.1.2
@@ -134,6 +136,8 @@ rfc3987==1.3.8
     # via jsonschema
 ruamel-yaml==0.17.21
     # via check-jsonschema
+ruamel-yaml-clib==0.2.12
+    # via ruamel-yaml
 six==1.16.0
     # via
     #   python-dateutil
@@ -197,6 +201,8 @@ urllib3==1.26.15
     #   transifex-client
 webcolors==1.13
     # via jsonschema
+zipp==3.20.2
+    # via importlib-metadata
 
 # The following packages are considered to be unsafe in a requirements file:
 # setuptools