Fixed towncrier template rendering

[kc611]

Resolves #9102,

As per the issue,
Adds a template for towncrier's auto-release notes generation and fixes towncrier build rendering issues.

[gmarkall]

Moved into the 0.58RC milestone as it fixes #9102 which is in it.

[sklam]

Thanks for the patch. I noticed a few things that need changing:

• heading level is not aligning with previous CHANGE_LOG entries
• the issue link not going to numba repo
• the section ordering can be improved

[sklam]

We should change the ordering of the sections. Currently, the CUDA session is going before the new_features. I found this the ordering is driven by the sections ordering in towncrier.toml. I suggest the following changes to it:

[[tool.towncrier.type]]
    directory = "highlight"
    name = "Highlights"
    showcontent = true

[[tool.towncrier.type]]
    directory = "new_feature"
    name = "New Features"
    showcontent = true

[[tool.towncrier.type]]
    directory = "improvement"
    name = "Improvements"
    showcontent = true

[[tool.towncrier.type]]
    directory = "np_support"
    name = "NumPy Support"
    showcontent = true

[[tool.towncrier.type]]
    directory = "cuda"
    name = "CUDA API Changes"
    showcontent = true

[[tool.towncrier.type]]
    directory = "performance"
    name = "Performance Improvements and Changes"
    showcontent = true

[[tool.towncrier.type]]
    directory = "bug_fix"
    name = "Bug Fixes"
    showcontent = true

[[tool.towncrier.type]]
    directory = "change"
    name = "Changes"
    showcontent = true

[[tool.towncrier.type]]
    directory = "deprecation"
    name = "Deprecations"
    showcontent = true

[[tool.towncrier.type]]
    directory = "expired"
    name = "Expired Deprecations"
    showcontent = true

[[tool.towncrier.type]]
    directory = "compatibility"
    name = "Compatibility Notes"
    showcontent = true

[[tool.towncrier.type]]
    directory = "doc"
    name = "Documentation Changes"
    showcontent = true

[[tool.towncrier.type]]
    directory = "infrastructure"
    name = "Infrastructure Related Changes"
    showcontent = true

[sklam]

The formatting here is not at the correct level for directly inclusion into CHANGE_LOG file. The documentation build shows the following in the index:

Notice that each section heading is at the same level of other release title heading.

[esc]

for a search and replace mistake

[esc]

fixup missing =

[esc]

Testing via #9135 yields:

[esc]

I have verified via #9135 that the new headings look good and the towncrier build --draft output can be used to partially auto-generate the new Numba change log.

sklam is AFK