Kill app before re-running on replit

Addresses an issue where re-running an instance on replit caused an
`[ERNO 98] Address already in use` error. Now it kills whatever process
is running on the default Whoogle port (5000) before running the app.

Fixes #531

.replit

@@ -1,3 +1,3 @@
 language = "bash"
-run = "pip install -r requirements.txt && ./run"
-onBoot = "pip install -r requirements.txt && ./run"
+run = "kill $(lsof -t -i:5000) > /dev/null 2>&1; pip install -r requirements.txt && ./run"
+onBoot = "kill $(lsof -t -i:5000) > /dev/null 2>&1; pip install -r requirements.txt && ./run"