Fix typo in is_instance_schema docstring #3985

Job	Run time
build on ${{ matrix.os }} (${{ matrix.target }} - ${{ matrix.interpreter \|\| 'all' }}${{ (((matrix.os == 'linux') && format(' - {0}', (((matrix.manylinux == 'auto') && 'manylinux') \|\| matrix.manylinux))) \|\| '') }})	0s
rust benchmarks	3m 3s
build pgo-optimized on ${{ matrix.os }} / ${{ matrix.interpreter }}	0s
build sdist	14s
build-wasm-emscripten	2m 36s
lint	53s
coverage	2m 14s
test-debug 3.11	57s
test on ubuntu	2m 14s
test-pydantic-integration	1m 43s
test-debug pypy3.10	1m 32s
test on macos	4m 44s
test on windows	4m 3s
test 3.7	2m 3s
test 3.8	2m 9s
test 3.9	2m 17s
test 3.10	2m 9s
test 3.11	2m 6s
test 3.12	2m 5s
test pypy3.7	2m 38s
test pypy3.8	2m 44s
test pypy3.9	2m 38s
test pypy3.10	2m 43s
test build on ${{ matrix.os }}	0s
test build on ${{ matrix.target }}-${{ matrix.distro }}	0s
inspect-pypi-assets	0s
check	2s
release	0s
	47m 47s

Provide feedback