Fix CRLF breakage in Linux build scripts

The Linux build host reads these scripts from a shared mount of the
Windows working tree, where autocrlf produces CRLF line endings. bash
then failed on `set -o pipefail` (trailing CR in the option name), and
the version parsed from version.go carried a trailing CR into the Docker
tag ("...:0.6.0\r": invalid reference format).

- Add .gitattributes forcing LF on *.sh so Windows checkouts stay LF.
- Strip CR from the version extraction in all three Linux build scripts.

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

scripts/build-linux.sh

@@ -3,7 +3,7 @@ set -euo pipefail
 
 # Optional first argument lets a developer or CI job choose the output path. The
 # default includes the application version and target platform.
-version="$(sed -n 's/^var Version = "\(.*\)"/\1/p' src/app/version.go)"
+version="$(sed -n 's/^var Version = "\(.*\)"/\1/p' src/app/version.go | tr -d '\r')"
 version="${version:-0.0.0-dev}"
 output="${1:-dist/linux/gosentry-${version}-linux-amd64}"
 mkdir -p "$(dirname "$output")"