Fix errors in python3-cariosvg overlay port.

Scripts/Ports/python3-cairosvg/portfile.cmake

@@ -22,13 +22,17 @@ endif()
 
 # Figure out from Python what its roots are in a mostly platform independent way. For Windows,
 # this should be the tools/python3 directory. In other cases, it should be CURRENT_INSTALLED_DIR.
-vcpkg_execute_in_download_mode(
+vcpkg_execute_required_process(
     COMMAND "${PYTHON_EXECUTABLE}" -c "import sys;sys.stdout.write(sys.exec_prefix)"
+    ALLOW_IN_DOWNLOAD_MODE
+    WORKING_DIRECTORY "${INSTALLED_PYTHON_PREFIX}"
     OUTPUT_VARIABLE INSTALLED_PYTHON_PREFIX
     LOGNAME query-prefix
 )
-vcpkg_execute_in_download_mode(
+vcpkg_execute_required_process(
     COMMAND "${PYTHON_EXECUTABLE}" -c "import sys,distutils.sysconfig;sys.stdout.write(distutils.sysconfig.get_python_lib(plat_specific=False,standard_lib=False))"
+    ALLOW_IN_DOWNLOAD_MODE
+    WORKING_DIRECTORY "${INSTALLED_PYTHON_PREFIX}"
     OUTPUT_VARIABLE INSTALLED_SITE_PACKAGES_DIR
     LOGNAME query-site-packages
 )
@@ -116,13 +120,16 @@ message(STATUS "Installing cairosvg from pip")
 file(TO_NATIVE_PATH "${CURRENT_PYTHON_PREFIX}" _PIP_PREFIX)
 vcpkg_execute_required_process(
     COMMAND "${PYTHON_EXECUTABLE}" -m pip install --prefix "${_PIP_PREFIX}" "cairosvg==${CAIROSVG_VERSION}"
+    ALLOW_IN_DOWNLOAD_MODE
+    WORKING_DIRECTORY "${CURRENT_PYTHON_PREFIX}"
     LOGNAME install
 )
 # Perform a sample import of cairosvg to ensure all this weird hacking actually works.
 message(STATUS "Testing cairosvg")
 set(ENV{PYTHONPATH} "${CURRENT_SITE_PACKAGES_DIR}")
 vcpkg_execute_required_process(
     COMMAND "${PYTHON_EXECUTABLE}" -c "import cairosvg"
+    ALLOW_IN_DOWNLOAD_MODE
     WORKING_DIRECTORY "${CURRENT_PYTHON_PREFIX}"
     LOGNAME test
 )

Scripts/Ports/python3-cairosvg/vcpkg.json

@@ -1,6 +1,7 @@
 {
   "name": "python3-cairosvg",
-  "version-string": "2.5.1",
+  "version-semver": "2.5.1",
+  "port-version": 1,
   "description": "CairoSVG is an SVG converter based on Cairo. It can export SVG files to PDF, EPS, PS, and PNG files.",
   "homepage": "https://cairosvg.org/",
   "dependencies": [