Remove explicit test on v1.8

[jishnub]

This is unnecessary now as v1 points to v1.8. Also, avoid duplicate tests on push+PR.

[codecov[bot]]

Codecov Report

Base: 86.90% // Head: 86.81% // Decreases project coverage by -0.08% :warning:

Coverage data is based on head (55e7020) compared to base (f19b903). Patch has no changes to coverable lines.

:exclamation: Current head 55e7020 differs from pull request most recent head 62a9177. Consider uploading reports for the commit 62a9177 to get more accurate results

Additional details and impacted files

```diff @@ Coverage Diff @@ ## master #137 +/- ## ========================================== - Coverage 86.90% 86.81% -0.09% ========================================== Files 10 10 Lines 1191 1191 ========================================== - Hits 1035 1034 -1 - Misses 156 157 +1 ``` | [Impacted Files](https://codecov.io/gh/JuliaMatrices/BlockBandedMatrices.jl/pull/137?src=pr&el=tree&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=JuliaMatrices) | Coverage Δ | | |---|---|---| | [src/broadcast.jl](https://codecov.io/gh/JuliaMatrices/BlockBandedMatrices.jl/pull/137/diff?src=pr&el=tree&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=JuliaMatrices#diff-c3JjL2Jyb2FkY2FzdC5qbA==) | `78.65% <0.00%> (-0.40%)` | :arrow_down: | Help us with your feedback. Take ten seconds to tell us [how you rate us](https://about.codecov.io/nps?utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=JuliaMatrices). Have a feature suggestion? [Share it here.](https://app.codecov.io/gh/feedback/?utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=JuliaMatrices)

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[jishnub]

Coverage failure points to this line: https://github.com/JuliaMatrices/BlockBandedMatrices.jl/blob/55e7020f12ef3778603adb3191ef72e931c52727/src/broadcast.jl#L14 Is this not being tested? Perhaps this is spurious, as the commit head is incorrect for some strange reason.

[dlfivefifty]

I think don't worry about coverage failure when its on the level of "noise"