Correctly compute project SHA when Manifest contains paths starting with `../`

[tpgillam]

Fixes https://github.com/julia-vscode/SymbolServer.jl/issues/285

This PR ensures that the project SHA is correct computed when an environment's Manifest contains relative paths starting with ../.

It also adds a test that would have caught the issue above.

To the reviewer: I bumped the patch version, since I'm used to releasing on every PR, but do advise what would be standard. (Naturally we're keen for the issue to be resolved in LanguageServer soon!)

---

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• [x] End-user documentation check. If this PR requires end-user documentation in the Julia VS Code extension docs, please add that at https://github.com/julia-vscode/docs.
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[pfitzseb]

Let's disable nightly CI temporarily so we can get this merged (unless you wanna debug and fix that failure too).

[tpgillam]

Let's disable nightly CI temporarily so we can get this merged (unless you wanna debug and fix that failure too).

Ha, I think I'll pass on looking at Julia nightly builds -- but why don't I add a commit just to temporarily disable that one? Then we can convince ourselves that nothing is broken at least.

Edit: Sorry, I misread -- I thought you'd said "disable CI", rather than "disable nightly CI"..!