Fix and consolidate MSRV handling

.github/workflows/tests.yml

@@ -167,15 +167,18 @@ jobs:
       - run: cargo test --target i686-unknown-linux-gnu --no-default-features --features http-client-rustls-native
         working-directory: ./lib/oxigraph
 
-  test_linux_msv:
+  test_linux_msrv:
     runs-on: ubuntu-latest
     steps:
       - uses: actions/checkout@v3
         with:
           submodules: true
+      - name: Read MSRV from Cargo.toml
+        id: metadata
+        run: echo "rust-version=$(sed -ne 's/rust-version *= *\"\(.*\)\"/\1/p' Cargo.toml)" >> $GITHUB_OUTPUT
       - uses: ./.github/actions/setup-rust
         with:
-          version: 1.70.0
+          version: ${{ steps.metadata.outputs.rust-version }}
       - run: rustup toolchain install nightly
       - run: rm Cargo.lock && cargo +nightly update -Z direct-minimal-versions
       - run: cargo test
@@ -304,15 +307,18 @@ jobs:
       - run: sphinx-lint docs
         working-directory: ./python
 
-  python_msv:
+  python_msrv:
     runs-on: ubuntu-latest
     steps:
       - uses: actions/checkout@v3
         with:
           submodules: true
+      - name: Read MSRV from Cargo.toml
+        id: metadata
+        run: echo "rust-version=$(sed -ne 's/rust-version *= *\"\(.*\)\"/\1/p' Cargo.toml)" >> $GITHUB_OUTPUT
       - uses: ./.github/actions/setup-rust
         with:
-          version: 1.70.0
+          version: ${{ steps.metadata.outputs.rust-version }}
       - run: rustup toolchain install nightly
       - uses: actions/setup-python@v4
         with:

lints/build_clippy_config.py

@@ -4,7 +4,6 @@ from urllib.request import urlopen
 
 import tomlkit
 
-MSRV = "1.74.0"
 LINT_BLACKLIST = {
     "absolute_paths",  # TODO: might be nice
     "alloc_instead_of_core",
@@ -63,6 +62,11 @@ LINT_BLACKLIST = {
     "wildcard_imports",  # TODO: might be nice
 }
 
+cargo_path = Path(__file__).parent.parent / "Cargo.toml"
+cargo_toml = tomlkit.parse(cargo_path.read_text())
+MSRV = cargo_toml["workspace"]["package"]["rust-version"]
+print(f"MSRV from the root Cargo.toml: {MSRV}")
+
 lints = set()
 with urlopen(
     f"https://rust-lang.github.io/rust-clippy/rust-{MSRV}/lints.json"
@@ -77,7 +81,5 @@ for flag in LINT_BLACKLIST:
     else:
         print(f"Unused blacklisted flag: {flag}")
 
-cargo_path = Path(__file__).parent.parent / "Cargo.toml"
-cargo_toml = tomlkit.parse(cargo_path.read_text())
 cargo_toml["workspace"]["lints"]["clippy"] = {lint: "warn" for lint in sorted(lints)}
 cargo_path.write_text(tomlkit.dumps(cargo_toml))