Add CHEP and PyHEP talks

[Saransh-cpp]

Description

Kindly take a look at CONTRIBUTING.md.

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Before Merging

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[eduardo-rodrigues]

Hello @Saransh-cpp, would it be possible to add these talks to our page https://scikit-hep.org/resources? In general we are rather out-of-date there, which is a shame. (There would be a lot more to add but I cannot be the only one to do this, as it then gets rather time consuming.) Many thanks.

[Saransh-cpp]

Hi, @eduardo-rodrigues! Happy to! I have created scikit-hep/scikit-hep.github.io#387 to add the talks in.