Allow installing packages system-wide in CI

I started seeing CI runs fail with "error: externally-managed-environment".

While in general it’s bad practice to install packages system-wide as this may interfere with system-managed packages, this is much less problematic in the one-off runners in CI.

As a workaround, I’ve disabled the warning when installing dependencies in CI.

.github/workflows/build.yml

@@ -34,6 +34,8 @@ jobs:
 
       - name: Install development dependencies
         run: make dev
+        env:
+          PIP_BREAK_SYSTEM_PACKAGES: 1
 
       - name: Check code formatting
         run: make format-check

.github/workflows/pr.yml

@@ -15,6 +15,8 @@ jobs:
 
       - name: Install development dependencies
         run: make dev
+        env:
+          PIP_BREAK_SYSTEM_PACKAGES: 1
 
       - name: Check code formatting
         run: make format-check