build: go back to not caching pip

This reverts commit 2b53612.

Author: nedbat

.github/workflows/coverage.yml

@@ -124,8 +124,11 @@ jobs:
         with:
           python-version: "${{ matrix.python-version }}"
           allow-prereleases: true
-          cache: pip
-          cache-dependency-path: 'requirements/*.pip'
+          # At a certain point, installing dependencies failed on pypy 3.9 and
+          # 3.10 on Windows.  Commenting out the cache here fixed it.  Someday
+          # try using the cache again.
+          #cache: pip
+          #cache-dependency-path: 'requirements/*.pip'
 
       - name: "Show environment"
         run: |
@@ -181,8 +184,11 @@ jobs:
         uses: actions/setup-python@e797f83bcb11b83ae66e0230d6156d7c80228e7c # v6.0.0
         with:
           python-version: "3.10" # Minimum of PYVERSIONS
-          cache: pip
-          cache-dependency-path: 'requirements/*.pip'
+          # At a certain point, installing dependencies failed on pypy 3.9 and
+          # 3.10 on Windows.  Commenting out the cache here fixed it.  Someday
+          # try using the cache again.
+          #cache: pip
+          #cache-dependency-path: 'requirements/*.pip'
 
       - name: "Show environment"
         run: |

.github/workflows/testsuite.yml

@@ -120,8 +120,11 @@ jobs:
         with:
           python-version: "${{ matrix.python-version }}"
           allow-prereleases: true
-          cache: pip
-          cache-dependency-path: 'requirements/*.pip'
+          # At a certain point, installing dependencies failed on pypy 3.9 and
+          # 3.10 on Windows.  Commenting out the cache here fixed it.  Someday
+          # try using the cache again.
+          #cache: pip
+          #cache-dependency-path: 'requirements/*.pip'
 
       - name: "Show environment"
         run: |