Try to fix Windows CI

GitHub says [0] that OpenSSL is already installed, so we *shouldn't need to futz
around with vcpkg, choco, etc to install that and slow things down further. But
it could be installed to C:\OpenSSL, C:\OpenSSL-Win64,
C:\Program Files\OpenSSL-Win64\, etc.

.github/workflows/rust.yml

@@ -9,7 +9,7 @@ on:
 env:
   CARGO_TERM_COLOR: always
 
-jobs:            
+jobs:
   build:
     strategy:
       matrix:
@@ -18,6 +18,13 @@ jobs:
 
     steps:
     - uses: actions/checkout@v3
+    - name: Set OPENSSL_DIR for Windows
+      if: startsWith(matrix.os, 'windows')
+      run:
+        dir C:\
+        DIR "C:\Program Files"
+        DIR "C:\Program Files (x86)"
+        echo "OPENSSL_DIR=C:\Program Files\OpenSSL-Win64" >> $GITHUB_ENV
     - name: Build
       run: cargo build --verbose
     - name: Run tests