Windows: Remove Program Files cache from ocrmypdf.exec

@lru_cache doesn't work here, so let's just remove it.

azure-pipelines.yml

@@ -34,15 +34,14 @@ stages:
             displayName: "Install system packages"
           - pwsh: |
               refreshenv
-              pip install --upgrade pip wheel
-              pip install -r requirements/main.txt -r requirements/test.txt .
-              tesseract --version
+              python -m pip install --upgrade pip wheel
+              python -m pip install -r requirements/main.txt -r requirements/test.txt .
             displayName: "Install Python packages"
           - pwsh: |
               refreshenv
               $env:pathext += ';.py'
               # -n auto helps Windows
-              python3 -m pytest -n auto --junitxml=test.xml --cov=ocrmypdf --cov-report=xml
+              python -m pytest -n auto --junitxml=test.xml --cov=ocrmypdf --cov-report=xml
             displayName: "Test"
           - task: PublishTestResults@2
             inputs:

src/ocrmypdf/exec/__init__.py

@@ -122,7 +122,6 @@ def get_version(program, *, version_arg='--version', regex=r'(\d+(\.\d+)*)', env
     return version
 
 
-@lru_cache(maxsize=1)
 def shim_paths_with_program_files(env=None):
     if not env:
         env = os.environ
@@ -134,7 +133,7 @@ def shim_paths_with_program_files(env=None):
         for dirname in os.listdir(program_files):
             if dirname.lower() == 'tesseract-ocr':
                 paths.append(os.path.join(program_files, dirname))
-            if dirname.lower() == 'gs':
+            elif dirname.lower() == 'gs':
                 try:
                     latest_gs = max(
                         os.listdir(os.path.join(program_files, dirname)),