Submodules: Use shallow clones

For releng, the history of submodules is irrelevant. If it is needed it
can still be fetched per repository after submodule initialization.

Signed-off-by: Alexander Diewald <diewald@fortiss.org>

.gitmodules

@@ -2,33 +2,41 @@
 	path = releng/org.fortiss.af3.target
 	url = https://git.fortiss.org/af3/target-definition.git
 	branch = master
+	shallow = true
 [submodule "bundles/af3"]
 	path = bundles/af3
 	url = https://git.fortiss.org/af3/af3.git
 	branch = master
 	fetchRecurseSubmodules = true
+	shallow = true
 [submodule "bundles/kernel"]
 	path = bundles/kernel
 	url = https://git.fortiss.org/af3/kernel.git
 	branch = master
 	fetchRecurseSubmodules = true
+	shallow = true
 [submodule "tests/af3"]
 	path = tests/af3
 	url = https://git.fortiss.org/af3/af3-tests.git
 	branch = master
+	shallow = true
 [submodule "features/af3"]
 	path = features/af3
 	url = https://git.fortiss.org/af3/af3-features.git
 	branch = master
+	shallow = true
 [submodule "features/tooling"]
 	path = features/tooling
 	url = https://git.fortiss.org/af3/tooling-features.git
 	branch = master
+	shallow = true
 [submodule "products/af3"]
 	path = products/af3
 	url = https://git.fortiss.org/af3/af3-products.git
 	branch = master
+	shallow = true
 [submodule "bundles/af3-rcp"]
 	path = bundles/af3-rcp
 	url = https://git.fortiss.org/af3/af3-rcp.git
 	branch = master
+	shallow = true