Fix version symlink

Author: tobiasdiez

VERSION.txt

@@ -1 +1 @@
-SageMath version 10.5.rc2, Release Date: 2024-11-30
+10.5.rc2

build/pkgs/sagelib/package-version.txt

@@ -1 +1 @@
-VERSION.txt
+../../../VERSION.txt

src/bin/sage-update-version

@@ -81,7 +81,7 @@ SAGE_VERSION_BANNER='$SAGE_VERSION_BANNER'
 EOF
 
 # Create a top-level VERSION.txt file, which some external utilities rely on
-echo "$SAGE_VERSION_BANNER" > "$SAGE_ROOT/VERSION.txt"
+echo "$SAGE_VERSION" > "$SAGE_ROOT/VERSION.txt"
 
 # Add version to the front of GitHub release assets URLs.
 SAGE_MINOR_VERSION=${SAGE_VERSION//.alpha*/}