Revert version update of cargo_metadata

This reverts the version of `cargo_metadata` to `0.15.4`, that undos PR
#483.

* update all GH checkout actions to version 4

.github/workflows/cache-zigs.yml

@@ -11,7 +11,7 @@ jobs:
     outputs:
       matrix-json: ${{ steps.set-matrix.outputs.matrix }}
     steps:
-      - uses: actions/checkout@v2
+      - uses: actions/checkout@v4
         with:
           repository: rinse-repeat/zig-gh-helper
           path: zig-helper      

.github/workflows/ci.yml

@@ -24,7 +24,7 @@ jobs:
           # MacOS
           - runs-on: macos-latest
     steps:
-      - uses: actions/checkout@v3
+      - uses: actions/checkout@v4
       - uses: dtolnay/rust-toolchain@stable
       - run: cargo test -- --skip args::args_tests::update_config_test_color_choice::case_4 --skip test_package
 
@@ -33,7 +33,7 @@ jobs:
 #    name: Check that clippy is happy
 #    runs-on: ubuntu-latest
 #    steps:
-#    - uses: actions/checkout@v3
+#    - uses: actions/checkout@v4
 #    - uses: dtolnay/[email protected]
 #      with:
 #        components: clippy
@@ -43,7 +43,7 @@ jobs:
     name: Check formatting
     runs-on: ubuntu-latest
     steps:
-    - uses: actions/checkout@v3
+    - uses: actions/checkout@v4
     - uses: dtolnay/rust-toolchain@stable
       with:
         components: rustfmt

.github/workflows/release.yml

@@ -19,7 +19,7 @@ jobs:
     outputs:
       matrix-json: ${{ steps.set-matrix.outputs.matrix }}
     steps:
-      - uses: actions/checkout@v2
+      - uses: actions/checkout@v4
         with:
           path: release-repo
       - id: set-matrix

cargo-geiger/Cargo.toml

@@ -17,7 +17,7 @@ maintenance = { status = "experimental" }
 anyhow = "1.0.70"
 cargo = "0.75.1"
 cargo-geiger-serde = { path = "../cargo-geiger-serde", version = "0.2.3" }
-cargo_metadata = "0.18.1"
+cargo_metadata = "0.15.4"
 cargo-platform = "0.1.2"
 colored = "2.0.0"
 console = "0.15.5"