Drop unused shebangs from repo test fixture scripts (#1375)

tests/fixtures/make_bare_repo.sh

@@ -1,4 +1,3 @@
-#!/bin/sh
 set -eu -o pipefail
 
 git init -q --bare

tests/fixtures/make_partial_repo.sh

@@ -1,4 +1,3 @@
-#!/bin/bash
 set -eu -o pipefail
 
 mkdir base

tests/fixtures/make_pre_epoch_repo.sh

@@ -1,4 +1,3 @@
-#!/bin/bash
 set -eu -o pipefail
 
 git init -q

tests/fixtures/make_repo.sh

@@ -1,4 +1,3 @@
-#!/bin/sh
 set -eu -o pipefail
 
 git init -q

tests/fixtures/make_repo_without_remote.sh

@@ -1,4 +1,3 @@
-#!/bin/sh
 set -eu -o pipefail
 
 git init -q