PEP 695: Fix template definition in C++ example

[acottuli]

Changed template <typename> to template <typename T> in the C++ generic class example.

• Change is either:
  • To a Draft PEP
  • To an Accepted or Final PEP, with Steering Council approval
  • To fix an editorial issue (markup, typo, link, header, etc)
• PR title prefixed with PEP number (e.g. PEP 123: Summary of changes)

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[python-cla-bot]

All commit authors signed the Contributor License Agreement.

[JelleZijlstra]

cc @erictraut