fix: pin rustpython to the same revision to fix cargo vendor (#2069)

I was trying to update ruff in nixpkgs and ran into this error when it was running `cargo vendor`
```
error: failed to sync

Caused by:
  found duplicate version of package `rustpython-ast v0.2.0` vendored from two sources:

        source 1: https://github.com/RustPython/RustPython.git?rev=62aa942bf506ea3d41ed0503b947b84141fdaa3c#62aa942b
        source 2: https://github.com/RustPython/RustPython.git?rev=ff90fe52eea578c8ebdd9d95e078cc041a5959fa#ff90fe52
```

ruff_dev/Cargo.toml

@@ -11,9 +11,9 @@ libcst = { git = "https://github.com/charliermarsh/LibCST", rev = "f2f0b7a487a87
 once_cell = { version = "1.16.0" }
 ruff = { path = ".." }
 ruff_cli = { path = "../ruff_cli" }
-rustpython-ast = { features = ["unparse"], git = "https://github.com/RustPython/RustPython.git", rev = "ff90fe52eea578c8ebdd9d95e078cc041a5959fa" }
-rustpython-common = { git = "https://github.com/RustPython/RustPython.git", rev = "ff90fe52eea578c8ebdd9d95e078cc041a5959fa" }
-rustpython-parser = { features = ["lalrpop"], git = "https://github.com/RustPython/RustPython.git", rev = "ff90fe52eea578c8ebdd9d95e078cc041a5959fa" }
+rustpython-ast = { features = ["unparse"], git = "https://github.com/RustPython/RustPython.git", rev = "62aa942bf506ea3d41ed0503b947b84141fdaa3c" }
+rustpython-common = { git = "https://github.com/RustPython/RustPython.git", rev = "62aa942bf506ea3d41ed0503b947b84141fdaa3c" }
+rustpython-parser = { features = ["lalrpop"], git = "https://github.com/RustPython/RustPython.git", rev = "62aa942bf506ea3d41ed0503b947b84141fdaa3c" }
 schemars = { version = "0.8.11" }
 serde_json = {version="1.0.91"}
 strum = { version = "0.24.1", features = ["strum_macros"] }