Update dependencies (#144)

1. Support broader version range for git2. Unlike regular dependencies,
for the native ones cargo refuses to have different versions of
libgit2-sys in the dependency tree, so it's better to be more permissive
here.
2. Check that protofetch compiles with MSRV and the minimal dependency
versions from Cargo.toml.
3. Use more recent toolchain by default.

.github/workflows/ci.yml

@@ -47,6 +47,23 @@ jobs:
       - name: Run cargo test
         run: cargo test
 
+  versions:
+    runs-on: ubuntu-latest 
+    steps:
+      - uses: taiki-e/install-action@v2
+        with:
+          tool: cargo-hack,cargo-minimal-versions
+
+      - name: Checkout sources
+        uses: actions/checkout@v3
+
+      - name: Cache rust dependencies
+        uses: Swatinem/rust-cache@v2
+
+      # Check with minimal dependency versions and MSRV from Cargo.toml
+      - name: Check minimal versions
+        run: cargo minimal-versions check --rust-version --features vendored-openssl,vendored-libgit2
+
   semver:
     runs-on: ubuntu-latest 
     steps:
@@ -65,7 +82,7 @@ jobs:
           GITHUB_TOKEN: ${{ secrets.GITHUB_TOKEN }}
 
   package:
-    needs: [ lint, test, semver ]
+    needs: [ lint, test, versions, semver ]
     strategy:
       fail-fast: false
       matrix: