Fix behavior when missing Pip (#6020) #1264

Job	Run time
Check Python types	3m 14s
Test Minimum Positron IPyKernel Dependencies (ubuntu-latest, 3.8)	4m 39s
Lint	4m 3s
Test Positron IPyKernel (macos-latest, 3.9)	2m 13s
Python Tests (ubuntu-latest, 3.8)	1m 46s
Test Positron IPyKernel (windows-latest, 3.10)	11m 34s
Test TypeScript (ubuntu-latest, 3.x, ts-unit)	3m 31s
Python Tests (ubuntu-latest, 3.12)	1m 37s
Test Positron IPyKernel (ubuntu-latest, 3.11)	3m 3s
Test TypeScript (ubuntu-latest, 3.x, functional)	4m 31s
Test Positron IPyKernel (ubuntu-latest, 3.12)	3m 33s
Test TypeScript (macos-latest, 3.x, ts-unit)	4m 0s
Test TypeScript (macos-latest, 3.x, venv)	3m 28s
Test TypeScript (macos-latest, 3.x, single-workspace)	4m 0s
Test TypeScript (macos-latest, 3.x, debugger)	2m 40s
Test TypeScript (macos-latest, 3.x, functional)	4m 8s
Test TypeScript (macos-latest, 3.x, smoke)	4m 57s
Test TypeScript (windows-latest, 3.x, ts-unit)	7m 49s
Test TypeScript (windows-latest, 3.x, functional)	8m 59s
	1h 23m 45s

Provide feedback