Fix incorrect version upgrade command in RELEASE.md (#179)

RELEASE.md

diff --git a/RELEASE.md b/RELEASE.md
index f4f1cc8..9a8e73c 100644
--- a/RELEASE.md
+++ b/RELEASE.md
@@ -58,7 +58,7 @@
 
 ```bash
 git checkout -b branch-X.Y
-sed -i 's/__version__.*/__version__=X.Y.0/' pulsar/__about__.py
+perl -pi -e "s/__version__.*/__version__='X.Y.Z'/" pulsar/__about__.py
 git add pulsar/__about__.py
 git commit -m "Bump version to X.Y.0"
 git push origin branch-X.Y
@@ -71,7 +71,7 @@
 
 ```bash
 git checkout branch-X.Y
-perl -pi -e "s/__version__.*/__version__=\"X.Y.Z\"/" pulsar/__about__.py
+perl -pi -e "s/__version__.*/__version__='X.Y.Z'/" pulsar/__about__.py
 git add pulsar/__about__.py
 git commit -m "Bump version to X.Y.Z"
 git push origin branch-X.Y
@@ -164,7 +164,7 @@
 
 ```bash
 git checkout main
-sed -i.bak 's/X.Y.0a1/X.Y+1.0a1/' pulsar/__about__.py
+perl -pi -e "s/X.Y.0a1/X.Y+1.0a1/" pulsar/__about__.py
 git add pulsar/__about__.py
 git commit -m "Bumped version to X.Y.0a1"
 ```