Replace use of taiki-e/install-action

The action updates very frequently with irrelevant changes (for other things it can install), making it more of a review burden than it's worth.

Author: Ortham

.github/workflows/ci.yml

@@ -4,8 +4,6 @@ on: [push, pull_request]
 
 env:
   CARGO_TERM_COLOR: always
-  TESTING_PLUGINS_VERSION: "1.6.2"
-  TESTING_PLUGINS_HASH: 01f7c8ae31e6527f0a1c1155d73653cf3af80a6af1e636ec0b33d7130e68182e
 
 permissions:
   contents: read
@@ -62,11 +60,18 @@ jobs:
   build:
     strategy:
       matrix:
-        os:
-          - windows-2025
-          - ubuntu-24.04
+        target:
+          - os: windows-2025
+            cargo_llvm_cov_sha256: dcf8e75e10b07f8348c900a600e429585cccaf4239533b7247a76c7ceaca0b3f
+          - os: ubuntu-24.04
+            cargo_llvm_cov_sha256: aa53c5963beb832f8ea04fea8dcbcece55a99e0c31a8d1e8d514d59ed5942160
 
-    runs-on: ${{ matrix.os }}
+    runs-on: ${{ matrix.target.os }}
+
+    env:
+      CARGO_LLVM_COV_VERSION: v0.6.19
+      TESTING_PLUGINS_VERSION: "1.6.2"
+      TESTING_PLUGINS_HASH: 01f7c8ae31e6527f0a1c1155d73653cf3af80a6af1e636ec0b33d7130e68182e
 
     steps:
       - uses: actions/checkout@v5
@@ -88,9 +93,14 @@ jobs:
         if: steps.cache-cargo.outputs.cache-hit != 'true'
 
       - name: Install cargo-llvm-cov
-        uses: taiki-e/install-action@d6d752794628f1e1fffa3c4d3c8874e06f043d50 # v2.62.15
-        with:
-          tool: cargo-llvm-cov@0.6.19
+        shell: bash
+        run: |
+          host=$(rustc -vV | grep '^host:' | cut -d' ' -f2)
+          curl --proto '=https' --tlsv1.2 -fsSLO "https://github.com/taiki-e/cargo-llvm-cov/releases/download/$CARGO_LLVM_COV_VERSION/cargo-llvm-cov-$host.tar.gz"
+
+          sha256sum -c <<< "${{ matrix.target.cargo_llvm_cov_sha256 }} cargo-llvm-cov-$host.tar.gz"
+
+          tar xzf cargo-llvm-cov-$host.tar.gz -C "$HOME/.cargo/bin"
 
       - name: Prepare test resources
         shell: bash