Use grep -E flag instead of -P flag so it works on all platforms

Author: qdm12

libevm/tooling/release/cherrypick.sh

@@ -27,7 +27,7 @@ set -o pipefail;
 
 SELF_DIR=$(dirname "${0}")
 # The format of the `cherrypicks` file is guaranteed by a test so we can use simple parsing here.
-CHERRY_PICKS=$(< "${SELF_DIR}/cherrypicks" grep -Pv "^#" | awk '{print $1}')
+CHERRY_PICKS=$(< "${SELF_DIR}/cherrypicks" grep -Ev "^#" | awk '{print $1}')
 
 commits=()
 for commit in ${CHERRY_PICKS}; do