chore(deps): update git2 to 0.20.0 (#10058)

Reverts #10045

This was not the straw that broke the camel's back, the introduction of
`turborepo-scm` to the [native
library](https://github.com/vercel/turborepo/pull/9950/files#diff-74cfbd08b3cb8946fb49f42e0ec3b53a441952c2189730a2fb508026f6d23ec4R21)
is what caused the native library release to fail.

Author: chris-olszewski

Cargo.lock

@@ -109,7 +109,7 @@ dunce = "1.0.3"
 either = "1.9.0"
 futures = "0.3.26"
 futures-retry = "0.6.0"
-git2 = { version = "0.19.0", default-features = false }
+git2 = { version = "0.20.0", default-features = false }
 hex = "0.4.3"
 httpmock = { version = "0.6.8", default-features = false }
 indexmap = "1.9.2"