Update CIPD version

Furthemore, move the CIPD version into a separate file so that it can be
updated independenty from the script itself.

Change-Id: Ifcc1c6a2daa25f37357ad54e2773bdafa2d67405
diff --git a/.cipd_version b/.cipd_version
new file mode 100644
index 0000000..3fd4ee6
--- /dev/null
+++ b/.cipd_version
@@ -0,0 +1 @@
+git_revision:76eadcd75c5ad2638e1fc098f81748aad150c7c0
diff --git a/cipd b/cipd
index 18f5bd2..beb4c47 100755
--- a/cipd
+++ b/cipd
@@ -7,7 +7,7 @@
 
 readonly SCRIPT_DIR="$(cd "$(dirname "${BASH_SOURCE[0]}")" && pwd)"
 
-readonly CIPD_CLIENT_VERSION="${CIPD_CLIENT_VERSION:-git_revision:508f70d14492573c37760381060bbb5fc7904bfd}"
+readonly CIPD_CLIENT_VERSION="${CIPD_CLIENT_VERSION:-$(cat ${SCRIPT_DIR}/.cipd_version)}"
 readonly CIPD_CLIENT_URL="${CIPD_CLIENT_URL:-https://chrome-infra-packages.appspot.com}"
 
 declare HOST_PLATFORM="$(uname -s | tr '[:upper:]' '[:lower:]')"