Use /usr/bin/env to find bash command. Signed-off-by: Tim 'mithro' Ansell <tansell@google.com>

diff --git a/open_pdks/build-magic.sh b/open_pdks/build-magic.sh
index 0a08fe6..5b50516 100755
--- a/open_pdks/build-magic.sh
+++ b/open_pdks/build-magic.sh

@@ -1,3 +1,4 @@
+#!/usr/bin/env bash
 # Copyright 2021 SkyWater PDK Authors
 #
 # Licensed under the Apache License, Version 2.0 (the "License");

diff --git a/open_pdks/build-open_pdks.sh b/open_pdks/build-open_pdks.sh
index 54cbd20..13db092 100755
--- a/open_pdks/build-open_pdks.sh
+++ b/open_pdks/build-open_pdks.sh

@@ -1,3 +1,4 @@
+#!/usr/bin/env bash
 # Copyright 2021 SkyWater PDK Authors
 #
 # Licensed under the Apache License, Version 2.0 (the "License");

diff --git a/open_pdks/build-skywater-pdk.sh b/open_pdks/build-skywater-pdk.sh
index d87e9e2..f4ddb44 100755
--- a/open_pdks/build-skywater-pdk.sh
+++ b/open_pdks/build-skywater-pdk.sh

@@ -1,3 +1,4 @@
+#!/usr/bin/env bash
 # Copyright 2021 SkyWater PDK Authors
 #
 # Licensed under the Apache License, Version 2.0 (the "License");

diff --git a/open_pdks/run.sh b/open_pdks/run.sh
index f6f9201..ecb05f2 100755
--- a/open_pdks/run.sh
+++ b/open_pdks/run.sh

@@ -1,4 +1,4 @@
-#!/usr/bin/bash
+#!/usr/bin/env bash
 # Copyright 2021 SkyWater PDK Authors
 #
 # Licensed under the Apache License, Version 2.0 (the "License");