Remove old excludes

These are detected as errors since the clean up was done[1] in
the requirements repository.

[1] 314734e938f107cbd5ebcc7af4d9167c11347406

Also remove the note about old pip's behavior because the resolver
in recent pip no longer requires specific order.

Change-Id: I5355c3fa692df22f4dc0c8aeac4fb12bae6dfec6

doc/requirements.txt

@@ -1,7 +1,4 @@
-# The order of packages is significant, because pip processes them in the order
-# of appearance. Changing the order has an impact on the overall integration
-# process, which may cause wedges in the gate later.
 openstackdocstheme>=2.2.0 # Apache-2.0
 reno>=3.1.0 # Apache-2.0
-sphinx>=2.0.0,!=2.1.0 # BSD
+sphinx>=2.0.0 # BSD
 sphinxcontrib-apidoc>=0.2.0  # BSD

requirements.txt

@@ -2,12 +2,9 @@
 # date but we do not test them so no guarantee of having them all correct. If
 # you find any incorrect lower bounds, let us know or propose a fix.
 
-# The order of packages is significant, because pip processes them in the order
-# of appearance. Changing the order has an impact on the overall integration
-# process, which may cause wedges in the gate later.
-pbr!=2.1.0,>=2.0.0 # Apache-2.0
+pbr>=2.0.0 # Apache-2.0
 platformdirs>=3 # MIT License
-cliff!=2.9.0,>=2.8.0 # Apache-2.0
+cliff>=2.8.0 # Apache-2.0
 dogpile.cache>=0.8.0 # BSD
 jsonschema>=3.2.0 # MIT
 keystoneauth1>=3.11.0 # Apache-2.0

test-requirements.txt

@@ -1,7 +1,4 @@
-# The order of packages is significant, because pip processes them in the order
-# of appearance. Changing the order has an impact on the overall integration
-# process, which may cause wedges in the gate later.
-coverage!=4.4,>=4.0 # Apache-2.0
+coverage>=4.0 # Apache-2.0
 fixtures>=3.0.0 # Apache-2.0/BSD
 requests-mock>=1.2.0 # Apache-2.0
 oslotest>=3.2.0 # Apache-2.0