Fix 3 14 and modernize CI

.github/workflows/main.yml

@@ -8,25 +8,25 @@ jobs:
     runs-on: ${{ matrix.os }}
     strategy:
       matrix:
-        python-version: ["2.7", "3.4", "3.5", "3.6", "3.7", "3.8", "3.9", "3.10"]
+        os: [ubuntu-latest]
+        python-version: ["3.9", "3.10", "3.11", "3.12", "3.13", "3.14"]
         include:
-          - os: ubuntu-latest
-          - os: ubuntu-18.04
-            flake: ==3.8
-            python-version: 3.4
-          - flake: ==3.9
-            python-version: 2.7
+          - os: ubuntu-22.04
+            flake: ==6.1
+            python-version: 3.9
+          - flake: ==7.3
+            os: ubuntu-latest
+            python-version: 3.14
 
     steps:
-      - uses: actions/checkout@v3
+      - uses: actions/checkout@v5
       - name: Set up Python ${{ matrix.python-version }}
-        uses: actions/setup-python@v3
+        uses: actions/setup-python@v6
         with:
           python-version: ${{ matrix.python-version }}
       - name: Install dependencies
         run: |
-          python -m pip install --upgrade pip
-          pip install flake8${{ matrix.flake }} six
-          python setup.py develop
+          python -m pip install --upgrade pip setuptools
+          pip install -e . flake8${{ matrix.flake }} six
       - name: Run tests
-        run: python -m unittest -v
+        run: python -m unittest -v

flake8_string_format.py

@@ -34,10 +34,19 @@ def _add_node(self, node):
         self.nodes += [node]
 
     def is_base_string(self, node):
-        typ = (ast.Str,)
-        if sys.version_info[0] > 2:
-            typ += (ast.Bytes,)
-        return isinstance(node, typ)
+        # Python 3.14 removed ast.Str/ast.Bytes, but older versions still use
+        # or expose them, so accept modern Constant nodes first and then fall
+        # back to whichever legacy node types still exist on this interpreter.
+        if isinstance(node, ast.Constant):
+            return isinstance(node.value, (str, bytes))
+
+        types = []
+        if hasattr(ast, 'Str'):
+            types.append(ast.Str)
+        if sys.version_info[0] > 2 and hasattr(ast, 'Bytes'):
+            types.append(ast.Bytes)
+
+        return isinstance(node, tuple(types))
 
     def visit_Str(self, node):
         # Constant with Python 3.8 uses the value-property

setup.py

@@ -44,7 +44,6 @@ def get_long_description():
         'License :: OSI Approved :: MIT License',
         'Operating System :: OS Independent',
         'Programming Language :: Python',
-        'Programming Language :: Python :: 2.7',
         'Programming Language :: Python :: 3',
         'Topic :: Software Development :: Libraries :: Python Modules',
         'Topic :: Software Development :: Quality Assurance',