ci: oneshot-test & pr-test: rebuild PyInstaller's bootloader

The PyInstaller's develop branch may contain changes to bootloader
that require bootloader to be rebuilt for PyInstaller at that commit
to be usable. So force bootloader compilation by setting the
PYINSTALLER_COMPILE_BOOTLOADER environment variable.

.github/workflows/oneshot-test.yml

@@ -109,6 +109,10 @@ jobs:
       # There doesn't seem to be a nice function to cast 'true' to true.
       fail-fast: ${{ github.event.inputs.fail-fast == 'true' }}
 
+    env:
+      # Rebuild bootloader when installing PyInstaller from develop branch
+      PYINSTALLER_COMPILE_BOOTLOADER: 1
+
     # Finally, the usual: setup Python, install dependencies, test.
     steps:
       - uses: actions/checkout@v2

.github/workflows/pr-test.yml

@@ -21,6 +21,11 @@ jobs:
         pyinstaller: ["https://github.com/pyinstaller/pyinstaller/archive/develop.zip"]
         os: ["macos-latest", "ubuntu-latest", "windows-latest"]
       fail-fast: false
+
+    env:
+      # Rebuild bootloader when installing PyInstaller from develop branch
+      PYINSTALLER_COMPILE_BOOTLOADER: 1
+
     steps:
       - uses: actions/checkout@v2