Flask updates, pin for py37 and add blinker

Pin Flask and Werkzeug for py3.7
They've removed compatibility upstream.
Added example to readme file because I had to go dig for one in the
commit history.
Add blinker to changelog URLs as it's a required dependency of Flask
now.

misc/requirements/README.md

@@ -19,4 +19,11 @@ Some examples:
 #@ filter: mypkg != 1.0.0
 #@ ignore: mypkg, otherpkg
 #@ replace: foo bar
+
+## Use the marker line to restrict the unpinned Flask requirement to python
+## 3.7. For python 3.7 add a specific version into the output.
+Flask
+# Python 3.7
+#@ markers: Flask python_version>="3.7"
+#@ add: Flask==2.2.5 ; python_version=="3.7.*"
 ```

misc/requirements/requirements-tests.txt

@@ -11,7 +11,7 @@ coverage==7.2.5
 exceptiongroup==1.1.1
 execnet==1.9.0
 filelock==3.12.0
-Flask==2.3.1
+Flask==2.3.1 ; python_version>="3.8"
 hunter==3.6.1
 hypothesis==6.75.1
 idna==3.4
@@ -53,5 +53,7 @@ tomli==2.0.1
 typing_extensions==4.5.0
 urllib3==1.26.15
 vulture==2.7
-Werkzeug==2.3.2
+Werkzeug==2.3.2 ; python_version>="3.8"
 zipp==3.15.0
+Werkzeug==2.2.3 ; python_version=="3.7.*"
+Flask==2.2.5 ; python_version=="3.7.*"

misc/requirements/requirements-tests.txt-raw

@@ -32,3 +32,8 @@ pytest-xdist
 tldextract
 
 #@ ignore: Jinja2, MarkupSafe, colorama
+# Python 3.7
+#@ markers: Flask python_version>="3.8"
+#@ add: Flask==2.2.5 ; python_version=="3.7.*"
+#@ markers: Werkzeug python_version>="3.8"
+#@ add: Werkzeug==2.2.3 ; python_version=="3.7.*"

scripts/dev/changelog_urls.json

@@ -161,5 +161,6 @@
   "asciidoc": "https://asciidoc-py.github.io/CHANGELOG.html",
   "pyproject_hooks": "https://pyproject-hooks.readthedocs.io/en/latest/changelog.html",
   "markdown-it-py": "https://github.com/executablebooks/markdown-it-py/blob/master/CHANGELOG.md",
-  "mdurl": "https://github.com/executablebooks/mdurl/commits/master"
+  "mdurl": "https://github.com/executablebooks/mdurl/commits/master",
+  "blinker": "https://blinker.readthedocs.io/en/stable/#changes"
 }