ci: Set BINSTALL_VERSION in install script tests

When running the install-script workflow in Github Actions, add matrix
options for not setting the variable, setting it to the latest release
with the `v` prefix, and setting it to the latest release without the
`v` prefix.

.github/workflows/install-script.yml

@@ -31,6 +31,7 @@ jobs:
       matrix:
         os: [macos-latest, ubuntu-latest]
         set_cargo_home: [t, f]
+        set_binstall_version: ['no', 'with-v', 'without-v']
 
     runs-on: ${{ matrix.os }}
 
@@ -44,6 +45,18 @@ jobs:
           mkdir -p "${CARGO_HOME}/bin"
           echo "CARGO_HOME=$CARGO_HOME" >> "$GITHUB_ENV"
 
+      - name: Set `BINSTALL_VERSION`
+        if: matrix.set_binstall_version != 'no'
+        env:
+          STRIP_V: ${{ matrix.set_cargo_home == 'with-v' && '1' || '' }}
+          GH_TOKEN: ${{ github.token }}
+        run: |
+          # fetch most recent release tag.
+          BINSTALL_VERSION="$(gh release list --json name --jq '[.[] | select(.name | startswith("v")) | .name] | first')"
+          if [[ -n $STRIP_V ]]; then BINSTALL_VERSION="${BINSTALL_VERSION#v*}"; fi
+          echo "Setting BINSTALL_VERSION=$BINSTALL_VERSION"
+          echo "BINSTALL_VERSION=$BINSTALL_VERSION" >> "$GITHUB_ENV"
+
       - name: Install `cargo-binstall` using scripts
         run: ./install-from-binstall-release.sh
         env:
@@ -59,6 +72,7 @@ jobs:
       fail-fast: false
       matrix:
         set_cargo_home: [t, f]
+        set_binstall_version: ['no', 'with-v', 'without-v']
 
     runs-on: windows-latest
 
@@ -73,6 +87,18 @@ jobs:
           mkdir -p "${CARGO_HOME}/bin"
           echo "CARGO_HOME=$CARGO_HOME" >> "$GITHUB_ENV"
 
+      - name: Set `BINSTALL_VERSION`
+        if: matrix.set_binstall_version != 'no'
+        env:
+          GH_TOKEN: ${{ github.token }}
+          STRIP_V: ${{ matrix.set_cargo_home == 'with-v' && '1' || '' }}
+        run: |
+          # fetch most recent release name.
+          BINSTALL_VERSION="$(gh release list --json name --jq '[.[] | select(.name | startswith("v")) | .name] | first')"
+          if [[ -n $STRIP_V ]]; then BINSTALL_VERSION="${BINSTALL_VERSION#v*}"; fi
+          echo "Setting BINSTALL_VERSION=$BINSTALL_VERSION"
+          echo "BINSTALL_VERSION=$BINSTALL_VERSION" >> "$GITHUB_ENV"
+
       - name: Install `cargo-binstall` using scripts
         run: ./install-from-binstall-release.ps1
         env:
@@ -86,6 +112,7 @@ jobs:
       fail-fast: false
       matrix:
         set_cargo_home: [t, f]
+        set_binstall_version: ['no', 'with-v', 'without-v']
 
     runs-on: windows-latest
 
@@ -100,6 +127,18 @@ jobs:
           mkdir -p "${CARGO_HOME}/bin"
           echo "CARGO_HOME=$CARGO_HOME" >> "$GITHUB_ENV"
 
+          - name: Set `BINSTALL_VERSION`
+          if: matrix.set_binstall_version != 'no'
+          env:
+            GH_TOKEN: ${{ github.token }}
+            STRIP_V: ${{ matrix.set_cargo_home == 'with-v' && '1' || '' }}
+          run: |
+            # fetch most recent release name.
+            BINSTALL_VERSION="$(gh release list --json name --jq '[.[] | select(.name | startswith("v")) | .name] | first')"
+            if [[ -n $STRIP_V ]]; then BINSTALL_VERSION="${BINSTALL_VERSION#v*}"; fi
+            echo "Setting BINSTALL_VERSION=$BINSTALL_VERSION"
+            echo "BINSTALL_VERSION=$BINSTALL_VERSION" >> "$GITHUB_ENV"
+
       - name: Install `cargo-binstall` using scripts
         shell: bash
         run: ./install-from-binstall-release.sh