[Bug Fix Release] raise warning if jax>0.6.2 is installed

[andrijapau]

Context:

Jax released a new version with a lot of breaking changes. Unfortunately our v0.42 release is not compatible with this version and so there are runtime errors.

ℹ️ : This PR was created by branching the v0.42.0 tag.

Description of the Change:

• The fix will check if the user has jax and if they do it will perform a version check to ensure compatibility.

>>> import pennylane as qml

~/Documents/pennylane/pennylane/__init__.py:29: RuntimeWarning: PennyLane is not yet compatible with JAX versions > 0.6.2. You have version 0.7.0 installed. Please downgrade JAX to <=0.6.2 to avoid runtime errors.

• We need to install the stable version of pennylane-lightning and pennylane-catalyst instead of the latest, because the latest version of these packages is now incompatible with this branch (they are using the pennylane.exceptions module for some custom exceptions). This change will not be merged into master.

Benefits: Better UI.

Possible Drawbacks: None.

[sc-96104]

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 99.68%. Comparing base (2a74df8) to head (17a0e94).
⚠️ Report is 1 commits behind head on v0.42.1-rc0.

Additional details and impacted files

@@             Coverage Diff              @@
##           v0.42.1-rc0    #7949   +/-   ##
============================================
  Coverage        99.68%   99.68%           
============================================
  Files              543      543           
  Lines            55314    55321    +7     
============================================
+ Hits             55140    55147    +7     
  Misses             174      174           

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[PietropaoloFrisoni]

Can confirm that importing PL with latest JAX results in a warning message:

>>> import pennylane as qml
RuntimeWarning: PennyLane is not yet compatible with JAX versions > 0.6.2. You have version 0.7.0 installed. Please downgrade JAX to <=0.6.2 to avoid runtime errors.
  warnings.warn(

💯

Not sure about the sphinx failures (I had to struggle with it even last time, and I had to downgrade)

[andrijapau]

Can confirm that importing PL with latest JAX results in a warning message:

>>> import pennylane as qml
RuntimeWarning: PennyLane is not yet compatible with JAX versions > 0.6.2. You have version 0.7.0 installed. Please downgrade JAX to <=0.6.2 to avoid runtime errors.
  warnings.warn(

💯

Not sure about the sphinx failures (I had to struggle with it even last time, and I had to downgrade)

I got around them by aliasing the imports as private (eb4a11d)

[andrijapau]

Tagging @jay-selby @Alex-Preciado as they were present on the last BF release PR. 👋🏼

[DSGuala]

Thanks for updating the error/warning messages 👍
Looks good to me.

[PietropaoloFrisoni]

🥇