Run pyupgrade --py36-plus

contrib/c-integer-semantics.py

doc/conf.py

examples/fortran/matmul-driver.py

examples/python/ispc-stream-harness.py

loopy/__init__.py

loopy/auto_test.py

loopy/check.py

loopy/cli.py

loopy/codegen/__init__.py

loopy/codegen/bounds.py

loopy/codegen/control.py

loopy/codegen/instruction.py

loopy/codegen/loop.py

loopy/codegen/result.py

loopy/compiled.py

loopy/diagnostic.py

loopy/expression.py

loopy/frontend/fortran/__init__.py

loopy/frontend/fortran/diagnostic.py

loopy/frontend/fortran/expression.py