Bump CI Rust version to 1.75.0

cargo tests in CI are [failing](https://github.com/sfackler/rust-postgres/actions/runs/12862700447/job/35858038081?pr=1198)
because of a dependency requirement:

```
Run cargo test --all
error: package `geo-types v0.7.15` cannot be built because it requires rustc 1.75 or newer, while the currently active rustc version is 1.74.0
Either upgrade to rustc 1.75 or newer, or use
cargo update [email protected] --precise ver
where `ver` is the latest version of `geo-types` supporting rustc 1.74.0
```

This bumps the Rust version so tests will run.

Author: allan2

.github/workflows/ci.yml

@@ -82,7 +82,7 @@ jobs:
       - run: docker compose up -d
       - uses: sfackler/actions/rustup@master
         with:
-          version: 1.74.0
+          version: 1.75.0
       - run: echo "version=$(rustc --version)" >> $GITHUB_OUTPUT
         id: rust-version
       - uses: actions/cache@v3