Avoid broken meson version 0.53.0 on Python 3.5.2
Avoid broken meson version 0.53.0 on Python 3.5.2

Meson 0.53.0 broke compatibility with Python 3.5.2

Error message with meson 0.53.0 in our Ubuntu 16.04/Python 3.5.2 CI
environment:

```
meson -Dtarget=sim-verilator -Dot_version=opentitan-snapshot-20191101-1-434-gb99db7f -Ddev_bin_dir=/home/vsts/work/1/a/build-bin/sw/device/sim-verilator -Dhost_bin_dir=/home/vsts/work/1/a/build-bin/sw/host --cross-file=/tmp/toolchain.dhA3HP.txt /home/vsts/work/1/a/build-out/sw/sim-verilator
Traceback (most recent call last):
  File "/usr/local/bin/meson", line 11, in <module>
    load_entry_point('meson==0.53.0', 'console_scripts', 'meson')()
  File "/usr/local/lib/python3.5/dist-packages/pkg_resources/__init__.py", line 489, in load_entry_point
    return get_distribution(dist).load_entry_point(group, name)
  File "/usr/local/lib/python3.5/dist-packages/pkg_resources/__init__.py", line 2852, in load_entry_point
    return ep.load()
  File "/usr/local/lib/python3.5/dist-packages/pkg_resources/__init__.py", line 2443, in load
    return self.resolve()
  File "/usr/local/lib/python3.5/dist-packages/pkg_resources/__init__.py", line 2449, in resolve
    module = __import__(self.module_name, fromlist=['__name__'], level=0)
  File "/usr/local/lib/python3.5/dist-packages/mesonbuild/mesonmain.py", line 25, in <module>
    from . import mconf, mdist, minit, minstall, mintro, msetup, mtest, rewriter, msubprojects, munstable_coredata
  File "/usr/local/lib/python3.5/dist-packages/mesonbuild/mconf.py", line 16, in <module>
    from . import coredata, environment, mesonlib, build, mintro, mlog
  File "/usr/local/lib/python3.5/dist-packages/mesonbuild/environment.py", line 32, in <module>
    from . import compilers
  File "/usr/local/lib/python3.5/dist-packages/mesonbuild/compilers/__init__.py", line 102, in <module>
    from .compilers import (
  File "/usr/local/lib/python3.5/dist-packages/mesonbuild/compilers/compilers.py", line 389, in <module>
    class CompilerArgs(typing.MutableSequence[str]):
  File "/usr/local/lib/python3.5/dist-packages/mesonbuild/compilers/compilers.py", line 658, in CompilerArgs
    def __eq__(self, other: typing.Any) -> typing.Union[bool, 'NotImplemented']:
    "Forward references must evaluate to types.")
  File "/usr/lib/python3.5/typing.py", line 312, in _type_check
    raise TypeError(msg + " Got %.100r." % (arg,))
TypeError: Forward references must evaluate to types. Got NotImplemented.
```

Works around #1288 for now.
Reported upstream at https://github.com/mesonbuild/meson/issues/6427

Signed-off-by: Philipp Wagner <5a4b10454c30419e54a1570be358a516ff84bb63@lowrisc.org>

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