Finish dropping pkg_resources

Closes #4467

README.asciidoc

@@ -91,8 +91,6 @@ unpatched vulnerabilities. Please use it carefully and avoid visiting untrusted
 websites and using it for transmission of sensitive data._
 * https://www.riverbankcomputing.com/software/pyqt/intro[PyQt] 5.12.0 or newer
   for Python 3
-* https://pypi.python.org/pypi/setuptools/[pkg_resources/setuptools] (being
-  phased out for qutebrowser v2.0.0)
 * https://palletsprojects.com/p/jinja/[jinja2]
 * https://pygments.org/[pygments]
 * https://github.com/yaml/pyyaml[PyYAML]

doc/changelog.asciidoc

@@ -32,7 +32,7 @@ Major changes
     if not used elsewhere - it's https://fdik.org/pyPEG2/[inactive upstream]
     and the repository was removed by Bitbucket).
   * Move the `pygments` dependency from required to optional.
-  * TODO: Move the `setuptools` dependency from runtime (for `pkg_resources`) to
+  * Move the `setuptools` dependency from runtime (for `pkg_resources`) to
     build-time.
   * For Python 3.6, 3.7 or 3.8, add a dependency on the `importlib_resources`
     backport.
@@ -66,8 +66,7 @@ Major changes
   used when using `:view-source` with QtWebKit, or when forcing it via
   `:view-source --pygments` on QtWebEngine. If it is unavailable, an
   unhighlighted fallback version of the page's source is shown.
-- TODO: The former dependency on the `pkg_resources` module (part of the
-  `setuptools` project) got dropped.
+- The former dependency on the `pkg_resources` module (part of the `setuptools`project) got dropped.
 - A new dependency on the `importlib_resources` module got introduced for
   Python versions up to and including 3.8. Note that the stdlib
   `importlib.resources` module for Python 3.7 and 3.8 is missing the needed APIs,

qutebrowser/misc/earlyinit.py

@@ -224,7 +224,6 @@ def _check_modules(modules):
 def check_libraries():
     """Check if all needed Python libraries are installed."""
     modules = {
-        'pkg_resources': _missing_str("pkg_resources/setuptools"),
         'jinja2': _missing_str("jinja2"),
         'yaml': _missing_str("PyYAML"),
         'dataclasses': _missing_str("dataclasses"),

qutebrowser/utils/utils.py

@@ -208,8 +208,8 @@ def read_file(filename: str, binary: bool = False) -> Any:
         return _resource_cache[filename]
 
     if hasattr(sys, 'frozen'):
-        # PyInstaller doesn't support pkg_resources :(
-        # https://github.com/pyinstaller/pyinstaller/wiki/FAQ#misc
+        # For PyInstaller, where we can't store resource files in a qutebrowser/ folder
+        # because the executable is already named "qutebrowser" (at least on macOS).
         fn = os.path.join(os.path.dirname(sys.executable), filename)
         if binary:
             f: IO