feat: declare minimum compatible version for fastapi (#216)

FastAPIBootstrapper._wrap_lifespan imports
fastapi.routing._merge_lifespan_context, which first exists in 0.112.2.
Every release below that fails at import of the bootstrapper module.

Author: lesnik512

pyproject.toml

@@ -70,7 +70,9 @@ free-all = [
     "lite-bootstrap[sentry,otl,logging,pyroscope]",
 ]
 fastapi = [
-    "fastapi",
+    # >=0.112.2 for fastapi.routing._merge_lifespan_context, which FastAPIBootstrapper._wrap_lifespan
+    # uses to chain teardown onto the user's lifespan. Private, so it can move without a deprecation.
+    "fastapi>=0.112.2",
 ]
 fastapi-sentry = [
     "lite-bootstrap[fastapi,sentry]",