(Airflow 3.3.1, 3.2.2, and 2.11.1) Upgraded the pip package from version

## Breaking Breaking _(Airflow 3.3.1, 3.2.2, and 2.11.1)_ Upgraded the `pip` package from version 23.2.1 to version 26.2.2\. This update is available in Managed Airflow (Gen 3) builds `composer-3-airflow-3.3.1-build.8`,`composer-3-airflow-3.2.2-build.12`, and `composer-3-airflow-2.11.1-build.25`and later, and in the Managed Airflow (Gen 2) image`composer-2.18.0-airflow-2.11.1` and later. This version includes security fixes and changes how custom PyPI packages are installed: * **PEP 440 version specifiers**: `pip` 26.2.2 enforces[PEP 440](https://peps.python.org/pep-0440/#version-specifiers) compliance and supports the `.*` wildcard only with `==` and `!=`. For example, use`gcsfs>=0.8` instead of `gcsfs>=0.8.*`. * **Isolated source builds**: source packages (`.tar.gz`) are always built in an isolated environment. If you install source packages from a private repository that is your only package index, make sure that the repository contains precompiled wheel packages (`.whl`) for `setuptools` and any other build dependencies (listed under `[build-system] requires` in`pyproject.toml`). Alternatively, publish your packages as `.whl` packages. As a temporary workaround to disable build isolation, add`no-build-isolation = false` to the `[global]` section of your `pip.conf`file. This workaround works only if the build dependencies are already installed in your environment. * **Legacy `pkg_resources` builds**: older source packages that rely on`pkg_resources` might fail to build. Use newer package versions with precompiled `.whl` packages, or for your own private packages, build them as `.whl` packages or update their build scripts so that they don't use the legacy `pkg_resources` module. Make sure that your custom PyPI packages are compatible with these changes before you upgrade your environment. If the installation of PyPI packages fails during an upgrade, your environment keeps running with its current version and packages.