changed npm install to npm ci when building the extension (#1029)

Extension/README.md

@@ -7,7 +7,7 @@ It allows users to track and monitor privacy-related browsing behavior.
 ## Installation
 
 ```bash
-npm install
+npm ci
 ```
 
 ## Instrumentation

scripts/build-extension.sh

@@ -10,7 +10,7 @@ eval "$(conda shell.bash hook)"
 conda activate openwpm
 
 pushd Extension
-npm install
+npm ci
 popd
 
 echo "Success: Extension/openwpm.xpi has been built"