[iOS] Fetch tags on install, not ipackage

This change removes a git command that requires a network connection from the ipackage target. It was used to ensure that CI has a tag to version the appledoc documentation with, so the same command has been added to install.sh, where a network connection is otherwise expected.

Fixes #2320.

scripts/ios/install.sh

@@ -3,6 +3,8 @@
 set -e
 set -o pipefail
 
+git fetch --tags
+
 mapbox_time "checkout_mason" \
 git submodule update --init .mason
 

scripts/ios/package.sh

@@ -115,7 +115,6 @@ if [ -z `which appledoc` ]; then
     exit 1
 fi
 DOCS_OUTPUT="${OUTPUT}/static/Docs"
-git fetch --tags
 DOCS_VERSION=$( git tag | grep ^ios | sed 's/^ios-//' | sort -r | grep -v '\-rc.' | grep -v '\-pre.' | sed -n '1p' | sed 's/^v//' )
 rm -rf /tmp/mbgl
 mkdir -p /tmp/mbgl/