Bump pip from 25.3 to 26.1 in /requirements

Bumps [pip](https://github.com/pypa/pip) from 25.3 to 26.1.
- [Changelog](https://github.com/pypa/pip/blob/main/NEWS.rst)
- [Commits](pypa/pip@25.3...26.1)

---
updated-dependencies:
- dependency-name: pip
  dependency-version: '26.1'
  dependency-type: indirect
...

Signed-off-by: dependabot[bot] <support@github.com>

Author: dependabot[bot]

requirements/build.txt

@@ -246,7 +246,7 @@ zope-interface==6.1
     #   gevent
 
 # The following packages are considered to be unsafe in a requirements file:
-pip==25.3
+pip==26.1
     # via pip-tools
 setuptools==78.1.1
     # via

requirements/checkformatting.txt

@@ -5,7 +5,7 @@
 #    pip-compile --allow-unsafe requirements/checkformatting.in
 #
 black==25.11.0
-    # via -r requirements/checkformatting.in
+    # via -r checkformatting.in
 build==1.0.3
     # via pip-tools
 click==8.1.7
@@ -15,7 +15,7 @@ click==8.1.7
 importlib-metadata==7.0.1
     # via pip-sync-faster
 isort==6.1.0
-    # via -r requirements/checkformatting.in
+    # via -r checkformatting.in
 mypy-extensions==1.0.0
     # via black
 packaging==23.2
@@ -25,10 +25,10 @@ packaging==23.2
 pathspec==0.12.1
     # via black
 pip-sync-faster==0.0.5
-    # via -r requirements/checkformatting.in
+    # via -r checkformatting.in
 pip-tools==7.5.2
     # via
-    #   -r requirements/checkformatting.in
+    #   -r checkformatting.in
     #   pip-sync-faster
 platformdirs==4.1.0
     # via black
@@ -44,7 +44,7 @@ zipp==3.19.1
     # via importlib-metadata
 
 # The following packages are considered to be unsafe in a requirements file:
-pip==25.3
+pip==26.1
     # via pip-tools
 setuptools==78.1.1
     # via pip-tools

requirements/coverage.txt

@@ -30,7 +30,7 @@ zipp==3.19.1
     # via importlib-metadata
 
 # The following packages are considered to be unsafe in a requirements file:
-pip==25.3
+pip==26.1
     # via pip-tools
 setuptools==78.1.1
     # via pip-tools

requirements/dev.txt

@@ -290,7 +290,7 @@ zope-interface==6.1
     #   gevent
 
 # The following packages are considered to be unsafe in a requirements file:
-pip==25.3
+pip==26.1
     # via pip-tools
 setuptools==78.1.1
     # via

requirements/format.txt

@@ -5,7 +5,7 @@
 #    pip-compile --allow-unsafe requirements/format.in
 #
 black==25.11.0
-    # via -r requirements/format.in
+    # via -r format.in
 build==1.0.3
     # via pip-tools
 click==8.1.7
@@ -15,7 +15,7 @@ click==8.1.7
 importlib-metadata==7.0.1
     # via pip-sync-faster
 isort==6.1.0
-    # via -r requirements/format.in
+    # via -r format.in
 mypy-extensions==1.0.0
     # via black
 packaging==23.2
@@ -25,10 +25,10 @@ packaging==23.2
 pathspec==0.12.1
     # via black
 pip-sync-faster==0.0.5
-    # via -r requirements/format.in
+    # via -r format.in
 pip-tools==7.5.2
     # via
-    #   -r requirements/format.in
+    #   -r format.in
     #   pip-sync-faster
 platformdirs==4.1.0
     # via black
@@ -44,7 +44,7 @@ zipp==3.19.1
     # via importlib-metadata
 
 # The following packages are considered to be unsafe in a requirements file:
-pip==25.3
+pip==26.1
     # via pip-tools
 setuptools==78.1.1
     # via pip-tools

requirements/functests.txt

@@ -265,7 +265,7 @@ zope-interface==6.1
     #   gevent
 
 # The following packages are considered to be unsafe in a requirements file:
-pip==25.3
+pip==26.1
     # via pip-tools
 setuptools==78.1.1
     # via

requirements/lint.txt

@@ -373,7 +373,7 @@ zope-interface==6.1
     #   gevent
 
 # The following packages are considered to be unsafe in a requirements file:
-pip==25.3
+pip==26.1
     # via
     #   -r tests.txt
     #   pip-tools

requirements/tests.txt

@@ -269,7 +269,7 @@ zope-interface==6.1
     #   gevent
 
 # The following packages are considered to be unsafe in a requirements file:
-pip==25.3
+pip==26.1
     # via pip-tools
 setuptools==78.1.1
     # via