update messaging on OTP isochrone support from 2.2 to 2.5

[e-kotov]

OTP releases that do support Isochrones:

https://docs.opentripplanner.org/en/v2.2.0/sandbox/TravelTime/
https://docs.opentripplanner.org/en/v2.3.0/sandbox/TravelTime/
https://docs.opentripplanner.org/en/v2.4.0/sandbox/TravelTime/
https://docs.opentripplanner.org/en/v2.5.0/sandbox/TravelTime/

Comment stating that Isochrone support is removed from OTP 2.x:
opentripplanner/OpenTripPlanner#4880 (comment)

Basically, the isochrones are gone starting with OTP 2.6.

So this PR will at least allow the users to use OTP 2.2-2.5, but long term there is no point in supporting the isochrones. Sad.

[e-kotov]

Also, OTP 2.2-2.4 are compatible with Java 17 or later:
https://docs.opentripplanner.org/en/v2.2.0/Basic-Tutorial/
https://docs.opentripplanner.org/en/v2.3.0/Basic-Tutorial/
https://docs.opentripplanner.org/en/v2.4.0/Basic-Tutorial/

Starting with 2.5, OTP claims that the minimum Java version is 21 or later:
https://docs.opentripplanner.org/en/v2.5.0/Basic-Tutorial/
https://docs.opentripplanner.org/en/v2.6.0/Basic-Tutorial/
https://docs.opentripplanner.org/en/dev-2.x/Basic-Tutorial/

Therefore I updated the messaging around these requirements.

[mem48]

I'm seeing an error when using isochones with OTP 1.5. Can you fix it?

[e-kotov]

I'm seeing an error when using isochones with OTP 1.5. Can you fix it?

Thanks for reviewing. I will double check.

[e-kotov]

It now works with OTP 1.5.

[e-kotov]

I'm seeing an error when using isochones with OTP 1.5. Can you fix it?

Hi @mem48 , this is a kind reminder about this fix and also about the suggestion in #121