Dependency version incompatibilities in notebooks cause import failures

Many imports in the notebooks are failing due to version incpompatibilies for [the routing with tket notebook](https://quantumai.google/cirq/experiments/qaoa/routing_with_tket) 



``` ---------------------------------------------------------------------------

ImportError                               Traceback (most recent call last)

[<ipython-input-26-f469bcac2048>](https://localhost:8080/#) in <module>

      1 import cirq

----> 2 import recirq

      3 import networkx as nx

      4 from cirq.contrib.svg import SVGCircuit

      5 import numpy as np



6 frames

[/usr/local/lib/python3.8/dist-packages/sphinx/util/rst.py](https://localhost:8080/#) in <module>

     19 from docutils.statemachine import StringList

     20 from docutils.utils import Reporter

---> 21 from jinja2 import Environment, environmentfilter

     22 

     23 from sphinx.locale import __



ImportError: cannot import name 'environmentfilter' from 'jinja2' (/usr/local/lib/python3.8/dist-packages/jinja2/__init__.py)



---------------------------------------------------------------------------

NOTE: If your import is failing due to a missing package, you can

manually install dependencies using either !pip or !apt.



To view examples of installing some common dependencies, click the

"Open Examples" button below.

---------------------------------------------------------------------------```



and when installing: 

`try:

    import recirq

except ImportError:

    !pip install -q git+https://github.com/quantumlib/ReCirq sympy~=1.6`



`  Preparing metadata (setup.py) ... done

ERROR: pip's dependency resolver does not currently take into account all the packages that are installed. This behaviour is the source of the following dependency conflicts.

notebook 5.7.16 requires jinja2<=3.0.0, but you have jinja2 3.1.2 which is incompatible.

flask 1.1.4 requires click<8.0,>=5.1, but you have click 8.0.0 which is incompatible.

flask 1.1.4 requires Jinja2<3.0,>=2.10.1, but you have jinja2 3.1.2 which is incompatible.`

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