Style: interpolated variables in strings need parentheses

[odow]

I propose that all interpolated variables in strings need parentheses.

Good:

x = 1
"Interpolated x=$(x) with parentheses.

Bad:

x = 1
"Interpolated x=$x without parentheses.

This stems from a potential breaking change between Julia 1.2 and Julia 1.3. See JuliaLang/julia#33044.

[mlubin]

Let's wait for a resolution on the Julia issue. Also, we don't need style points to cover pieces of code that don't compile, we should just run 1.3 on CI.

[odow]

Okay. This is fixed on latest Julia master, so we can probably close.